Thermal Decomposition of (Presumed) Bismethylene Diazene Citation Hawke, David Harry (1977) Thermal Decomposition of (Presumed) Bismethylene Diazene. Master's thesis, California Institute of Technology. doi:10.7907/2F5K-AV65. https://resolver.caltech.edu/CaltechTHESIS:11242009-081150564 Abstract Thermal high temperature and base induced low temperature de-composition of 1-sulfonamido-2, 3-dimethylaziridines (2, 3) and low temperature oxidation of 1-amino-2,3-dimethylaziridines (4) gives 2-butenes as the major hydrocarbon products (70-99%). The stereo-chemistry of the products is consistent with a stepwise pathway for decomposition of the presumed intermediate bismethylene diazenes (1). Item Type: Thesis (Master's thesis) Subject Keywords: (Chemistry) Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemistry Thesis Availability: Public (worldwide access) Research Advisor(s): Dervan, Peter B. Thesis Committee: Unknown, Unknown Defense Date: 25 August 1976 Funders: Funding Agency Grant Number Caltech Earle C. Anthony Fellowship (1974-1975) UNSPECIFIED Record Number: CaltechTHESIS:11242009-081150564 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:11242009-081150564 DOI: 10.7907/2F5K-AV65 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 5399 Collection: CaltechTHESIS Deposited By: Tony Diaz Deposited On: 01 Dec 2009 18:24 Last Modified: 18 Sep 2024 23:12 Thesis Files Preview PDF - Final Version See Usage Policy. 1MB Repository Staff Only: item control page

THERMAL DECOMPOSITION OF (PRESUMED) BISMETHYLENE DIAZENE Thesis by David H. Hawke In Partial Fulfillment of the Requirements for the Degree of Master of Science California Institute of Technology Pasadena, California 1977 Submitted August 25, 1976 Acknowledgement The author wishes to thank the Division of Chemistry and Chemical Engineering for the award of an Earle C. Anthony Fellowship (1974-75), and various assistantships. A special tanks is due Professor Peter B. Dervan for his enduring patience. x Sy as) >) 4 [o) fy Abstract Thermal high temperature and base induced low temperature de- composition of 1-sulfonamido-2, 3-dimethylaziridines (2, 3) and low temperature oxidation of l-amino~-2, 3-dimethylaziridines (4) gives 2-butenes as the major hydrocarbon products (70-99%). The stereo- chemistry of the products is consistent with a stepwise pathway for decom- position of the presumed intermediate bismethylene diazenes (1) : Table of Contents Abstract Introduction Results and Discussion Experimental References Appendix 22 37 39 Introduction N-nitrenes! (1, 1-diazenes) have been proposed as intermediates in certain reactions of 1, 1-disubstituted hydrazines, although none have ever been isolated or observed directly. Cyclic 1,1-diazines have been implicated as intermediates for the generation of presumed diralicals: tetramethylene” and trimethylene® diazenes for tetramethylene and trime- thylene diradicals, respectively. In these cases hydrocarDon products have been found to be very similar to the products resulting from de- composition of the corresponding cyclic azo-compounds (1,2-diazenes). Reported attempts to generate the smallest homologue in this series, bismethylene diazene, have met with some success. Deamination of 2,3-dimethylaziridines by difluoramine at 0° affords 2-butenes with at least 96% retention of configuration‘. Oxidation of 1-amino-2, 3-diphenyl- aziridines with activated manganese dioxide reportedly” gives only re- tention in the trans case, and predominant (85:15) inversion in the cis case. Lead tetraacetate® gives predominant retention (99. 0% in the cis, 98.5% in the trans case). In order to determine the effects of mode of generation, temperature, phase, and substitution on the behavior of bismethylene-1, 1-diazene thermal decompositions, we sought to further study the dimethyl substituted 1,1-diazene by «-elimination at high and low temperatures, and oxidation at low temperatures. Similar three membered ring fragmentations proceed in Some cases with retained, and in at least one case, mixed stereochemistry (see Table I). The possibility of concerted fragmentations in 1, 1-diazene decompo- sitions was stressed by Freeman’. According to the Woodward and Hoffman rules of orbital symmetry, non-linear chelotropic extrusion is allowed, and the linear pathway is forbidden. However, stereospecific diradical 7 Table I: Three Membered Ring Fragmentations. Compownd® r/iP(%) I. Conditions References —n~ __[eN-NO 99.0/1. 0 -23°to 25° solution 9 REN trazs 99/1 0° solution 6 R~ cis 97.5/2.5 + Al e} | >N=N 96/4 0° neat 4 oS 99/1 60° melti _ {S05 / 60 melting 19 p | S05 99/1 25 solution 11 an cis 90/10 300° injection 8 _ps=0 trans 60/40 port — _ \ UN N=NA 99.5/0.5 9H refivx solution 12 HN Pe) c | INL trans” 100/0 -29° solution 13 R— Pp R=M2 99/1 CH,Cl, solution 6 Rp L-N-N R=P198.5/1.5 reflux (a) These results are for both cis and trans isomers, except as entered; P = C,H,, A = p-NO,C,U,. (b} Retention/taversion = r/i. (c) The cis isomer undergoes exclusive 2, 3-cycloelimina‘ion. 8 intermediates remain a possibility. A temperature effect might be expected, so examination at both high and low temperatures would be informative. The sulfur monoxide® extrusion is the only case so far for which a concerted mechanism can be clearly ruled out, but in this case other reactions interfere at low temperatures. Results and Discussion The prepa~ation of the substrates involved in this are outlined in Scheme 1 below. Scheme 1: Preparation of Substrates OR IN a LL —> _[EN-NHp = > __DN-NHR 5, 6 es 2.3 R=H Ms? R= Ms_ Ts? erythro 6a 5a cis 4a 3a 2a threo 6b 5b trans 46 3b 6 2b a} Ms = 8O.CH, ; - b) TS”= SO,C,H, ~~ The commercially available diols, 6 , were converted to the crys- talline dimethanesulfonates®, 9 , in good yield by treatment with methane- sulfonyl chloride in pyridine. Reaction of the dimethanesulfonates with hydrazine gave 30-50% yields of the substituted aziridines ®, 4, which upon treatment with p-toluenesulfonyl chloride (for 2) or methanesulfonyl chloride (for 3 ) gave the sulfonamidoaziridines? +. The aminoaziridines, 4, were also available by an independent route, via hydrazinolysis of the phthalimidoaziridines, 7. These were prepared by oxidation of N-amino-~ phthalimide in the presence of cis- or trans-2-butene. The aminoaziridines prepared by the first route exhibited properties identical to those prepared by the second method. Satisfactory infrared, nuclear magnetic resonance, and mass spectral data could be obtained for 1-sulfonamido-cis-2, 3-di- methylaziridine, 3a , but elemental analysis (C, H, N) was low (compound 9 decomposes to volatile products). The unstable trans isomer, 3b , suffered decomposition in the NMR probe (ca 40°, t, /% 1 hour) and attempts to obtain a solid sample of this material failed. The crystalline p-toluene- sulfonyl derivatives, 2 , were somewhat more stable, and could be pur- ified by preparative thin-layer chromatography on silica gel. The spec- tral data were satisfactory, but the cis isomer showed only decomposition in the inlet of the mass spectrometer. Thermolyses of the toluenesulfonamido-aziridines, 2 , and methane- sulfonamido-aziridines, 3 , in benzene solution were carried out ina heated tube (305-330°, 30 seconds). Volatile products were trapped at 77K, distilled, and analyzed by analytical vapor phase chromatography. The products of these decompositions can be found in Table II. A combined gas chromatography-mass spectroscopy experiment performed on the products of decomposition of 2a identified the bulk of the minor products (components 20.5%) as ethane, propene, and C,Hie isomers (see experimental). A benzene solution of methanesulfinic acia!® was found to isomerize cis-butene in the hot tube (as well as in solution), giving rise to suspicion that product distributions might be due to isomerization by that by-product. As a test, cis-3-hexene was copyrolysed with 1-methanesulfonamido-cis- 2,3-dimethylaziridine, and cis-2-butene was copyrolysed with 1-methane- sulfonamido-cis-2, 5-dimethylpyrolidine. These experiments showed little (1.5% for cis-2-butene at 306°, 3.5% at 439°) or no (less than 0.5%) isomerization of the olefins, analyzed by gas chromatography. The ratio of cis and trans butenes produced under these conditions (305-330, some data at 419°) does not show a significant temperature dependence. The close correspondence of product ratios (of 2-butenes) from 2 or 10 3 and the related episulfoxides® supports the hypothesis that the mechanisms | may be similar. It was proposed that the episulfoxides fragment in step- , wise fashion, perhaps via 9’ (Scheme 2). The intermediate diazeny! radi- cal, 1', analogous to 9', could rotate about the C,-C, bond, then lose Scheme 2 8 | 9 9° ~s os —Don-nne —> DAN > _]ONg at | nitrogen to give olefin of the opposite stereochemistry. A kinetic scheme linking the decomposition of each isomer can be written (Scheme 3). Scheme 3 ~ ta ~ tb “sn i oe wo << o 3 St Assuming back reactions to 1,1-diazenes to be negligible, a steady state analysis of the system yields relative rates of cleavage and rotation for 11 Table II: Chamber pyrolyses“, N i y) 3 N-NHR cis oa 2a a trans 2b 3b 2, 3. Compound T a-butane 1-butene t-butene” c-butene” other unident© 2a 308° - 2.3 14.1 85.9 0.5 0.1 2 310° - 1.2 58.7 41.3 0.1 0.1 3a 310° 0.02 2.0 13.1 86.9 4.0 1.0 3a 419° 0.09 1.4 13.8 86.2 19.4 0.5 3b 330° - 5.8 65.1 34,9 7.5 = 3b 435° - 6.7 72.3 27.7 28.7 = 3a° 330° - 4.5 17.0 83.0 6.2 - Bat 306° Og - 1.5 98.5 - ga" 439° - 3.5 96.5 - Typical absolute yields of hydrocarbons was 30-60%. The sum of 2-putenes normalized to 100%. Cis-3-hexene (98. 4% cis) added was recovered 98. 0% cis. Copyrolysis of cis-2-butene, 8a, and 1-methanesulfonamido-cis-2, 5- dimethylpyrrolidine was reportéd in footnote 9 of reference 2b. Unidentified hydrocarbons. 12 each diradical from the product ratios resulting from each isomer. This treatment ignores possible side reactions of the diazenes, diazenyl radi- cais, and product olefins. The algebraic steps required are detailed in an appendix. Derived relationships and calculated rate ratios are in Table Ii. The temptation to use Fischer projections to estimate relative rotational barriers is overwhelming, and is diagrammed in Scheme 4. For the diazene (a,b,c,d, of Scheme 4) and episulfoxide cases, this Scheme 4: Fischer Projections CHIN CH 4 CH CH H °~ Hz 4 e CHCH CH CH CH ¥ KOH HTS ; 3 H3 R H R H R H R | £. fi g h approach seems to work. The problem arises, however, with its extension to the case of 1, 2-dimethyl-tetramethylenediyl2° (e,f,g,h, of Scheme 4), from which we would expect similar behavior, but observe the reverse. The distribution of steric bulk (Scheme 5) about the terminae of the incipient 2-butene does correspond consistently: cleavage appears to be faster than rotation if the bulky groups are cis (2.6-5.0), while the rates are com- petitive (1.2-1.5) if the bulky groups are trans. This may be evidence of steric attraction? 13 Table Ill: Cleavage to Rotation ratios for 1' —— »_ _{, Noe 1' Definitions®: o& = (r/i) cis 6 = (r/i) trans R, = k,/K, R, = *4/Ky E quations* : fo - 1 R, = --- B+ 1 R, = a (7 7-1 a+ 1 Species aK i) R, R, 2 6.09 1,42 3.16 1.08 3 6.14 1. 86 3.64 1. 46 9? 9. 09 1.50 5. 00 1.25 Tetramethylene~ - - 1.2 2.5 diradical (a) See Scheme 3 and Appendix. (b) Calculated from data in reference 8. (c) Reference 25. 14 Scheme 5 Qe fo DB Briefly, the high temperature decomposition of 2 and 3 gives products consistent with diazene intermediates which fragment by a stepwise mech- anism. It might therefore be possible to interpret Freeman's diazene experiment* in terms of a stereospecific diradical intermediate. There follows a description of attempts to independently generate similar inter- mediates at lower temperature (0-25°) in order to make a direct compar- ison with Freeman's diazene’. In an early solution phase experiment‘, T. Uyehara of the Dervan Group thermolysed 1-sulfonamido-cis-2, 3-dimethyl-aziridine, 3a, in benzene in a sealed tube (see Table IV). The predominant inversion ob- served could be real, or due to isomerization of the first formed olefins by methanesulfinic acid. A sample of the acid was prepared! by the reaction of water with methanesulfinyl chloride, and was found to iso- merize cis-2-butene in benzene solution (sealed tube) at 100°. A recent report." has confirmed that sulfinic acids are capable of catalytic iso- merization of olefins. Further solution phase decompositions were carried out in the presence of at least one equivalent of base. Base induced decompositions of 3a, 2a, 20, were carried out in diglyme in sealed tubes under nitrogen atmosphere. The usual base was 2N sodium: 2-n-butoxy ethoxide in 2-n-butoxyethanol. Products were 15 1 Table IV: Thermolysis 4 of 1-sulfonamido-cis-2, 3-dimethylaziridine, 3a. —™ N-NHSO5CH3 ~ 3a_ t(min) T t-butene__c-butene__vield (%) 15 180° 56 44 51 30 190° 64 36 45 16 distilled at high vacuum and analyzed Dy vapor phase chromalography. Results are entered in Tabie V. The product olefin ratios from the trans isomer, 2b , show predominant trans stereochemistry. A consistent explanation is that the trans diazene, tb , is formed, and fragments to olefin with a high degree of retention. This observation fits with Freemans* of at least 96% retention. Products from decomposition of the cis isomers are vaviable. Added olefin was recovered unchanged, hence it seemed unlikely that the products were scrambiing under the reaction conditions. In sclution, the mechanism of formation of diazenes from sulfonylhydrazines has been proposed to be ionization to the diazenium ion and sulfinate ion, followed by proton traasfer to give the diazene (as in Scheme 6). If deprotonation at nitrogen is slow Scheme 6_ + = B: + SN-NHSO,R E2DNENH + S028 => ~DNeN fo Ne | + A compared with the other chemistry available to the diazeniuni ion, the diazene will be superseded by intermediates whose decomposition products are difficult to precisely predict. The competing pathways orobably imvo.ve ring cleavage, as indicated, Scheme 5. “That proton transfer may in iect be rate limiting is suggested oy the pase dependence sStiown in the last two entries of Tavle V. The stronger pase, potassium i-bucvoxide, gives more retention, 17 Table V: Base Induced Decomposition Data®: b R=Ts R=Ms _DANHR ens 8 2,3 Compound __T __t* ___butane _1-butene _ t-butend! _¢-butene" other 3a 25° 2.5h 6.1 0.3 58. 0 42.0 4.3 3a° 25° 2h - 2.3 42.0 58.0 7.6 2b 0° 2.5h 0.1 0.1 98. 0 2.0 2.0 2b 105° 5m 0.1 - 95.6 4.4 0.4 2at 105° 5m - 60.4 39.6 0.4 2a 105° 5m - 6.7 32.7 67.3 0.75 (a) Typical absolute hydrocarbon yields were 20-75%. (b) The base used was 2N sodium 2-{n-butoxy) ethoxide in 2-n-butoxy ethanol, unless otherwise noted. (c) h=hours, m=minutes. (d) The sume of 2-butenes was normalized to 100%. (e) Added cis-3-hexene (98.4 cis) was recovered, 98.6% cis. (f{) Diisopropyl ethylamine was uged as the base. (g) Potassium t-butoxide was used as the base. 18 but also more 1-butene, presumably via a base-assisted ring cleavage pathway. It was expected that oxidation of the aminoaziridines, 4 , would proceed without the complications encountered in the base induced frag- mentations discussed above. The oxidant primarily studied was activated manganese dioxide. The rate of oxidation with yellow mercuric oxide was inconveniently slow. Results and conditions of oxidation experiments are detailed in Table VI. The solvent, n-hexane, and aminoaziridine, 4a or 4b , were de- gassed and distilled onto degassed oxidant. After the reaction time, products were distilled and analysed as before. This route gave almost entirely C, hydrocarbons, other products were always less than 1.5%. The appearance of butane in the products deserves some note, as it is not an expected product from the diazene, and occured only negligibly in the hot tube and base induced decompositions. The mechanism of MnO, oxi- dations is not well understood . Oxidation of 1, 1-substituted hydroazines is usually explained by invoking diazene intermediates without mention of the mechanism of formation of these intermediates from the hydrazines. A reasonable mechanism (Scheme 7) can be suggested: ring cleavage of the one election oxidation product of 4 would give a radical species which Scheme 7 oN, —~N Ss — Tt 4 A 8 : | NoH J FF 19 Table Vi: Ox:dation of 1-Amino-2, 3-dimethylaziridines, 4. _D-N-NH is trans 4b 4 isomer* | > T Mno,,° n-butane I1-butene t butene@ c-butene other cis 4hitas:~*~<C«~S SW 06 ~=—s«d12.0S—«B_lD—«i dS cis 2n =? XS 0.3 0.1 9.8 90.2 0.2 butenes” 2h 0° xS - - 9.6 90.4 - cis 30m 0° xs - - 21.6 73.4 v. i cis = dm S?s=S 0.07 - 11.3 88.7 0.2 cis) 4m 0° cal - - 17.0 83.0 9.2 trans 2h 0° xs 2.5 0.9 89. 4 10.6 0.3 trans® 40m 0° xs 10 - 81.9 181 - trans" 4m 0° xs 5.0 1.0 13.0 37.0 9.3 trans* 4m 0° ca 1 29 - 83.0 17.0 1.3 (a) Cis = 4a, trans= 4b, see note (e). (0) 1 = hoars, m = minutes. (c) xs = 10-20 equivalents, ca 1 = about equivaleat. (1: The sum of 2-butenes normalized to 100%. {e} The product from the orzcedias tisting was re-subjected to the reaction conditions. (f) Cis-2-venteue (98.0% cis) was recovered 97.6% cis. (g} Added cis-2?-pentene (98.0% cis) was recovered 97.7% cis. nh} Added 2:5+2-pentere (98. I% cis) was recovered 97.8% cis. 20 (i) Added cis-2-pentene (98. 0% cis) was recovered 97.7% cis. (j) In this experiment, unreacted starting material (4a) was found to be at least 99% cis. ~ (k) In this experiment, unreacted starting material (4b) was found to be ca 96.6% trans. 21 could absiract a hydrogen, then lose nitrogen to give n-butane. Cis-2- pentene was recovered essentially unchanged from these oxidations. Thermal Decomposition of 1-amino-trans-2, 3-dimethylaziridine, 4b. It has been observed during the handling of these and other amino- aziridines, that they are thermally unstable, decomposiag to give olefins. In this case, there is evidence for decomposition to cis- and trans-2-butene (injection port, 150-200°, 10-15%), and also for one-bond ring opening (see experimental). Trans-2,3-diphenylaminoaziridine has been reported to evolve trans-stilbene at 25°. It is possible that some N,H, species is intermediate in the production of non-hydrocarson compounds, and it has been suggested that the parent, aminonitrene, is formed (see Scheme 3). Ifit was formed, the aminonitrene might be expected to either dis- proportionate directly to nitrogen and hydrazine, or rearrange to the more stable diimide. The aminonitrene might be directly observable, but diimice?” would be expected to be. Indeed, hydrazine is observed by gas chroma- tography during analysis of these compounds, 4, and molecular nitrogen 18 easily distinguishable in the photelectron spectrum of gaseous 4 passed over a neated filament (ca 400-650°). These facts are consistent with the known disproportionation of diimide. Scheme 8 ~SN-NHS 3 - 45 5, — + | | | + N=NHy > HN=ENH —> No + Ast, 200 Experimental Melting points were determined on a Thomas-Hoover capillary melting point apparatus, and are uncorrected. Infrared spectra were re- corded on a Perkin-Elmer mode! 257 grating infrared spectrophotometer. Nuclear magnetic resonance spectra were recorded on a Varian Associates A-60 nuclear magnetic resonance spectrometer operating at 60 MIIz (reported in § from TMS). Elemental analyses and mass spectra were performed and recorded by the Caltech microanalytical services, under the direction of Dr. Susan Rottschaffer. Analytical vapor phase chromato- graphy equipment employed included a Hewlett-Packard model 5700A gas chromatograph, equipped with a flame ionization detector and a Hewlett- Packard model 3370B electronic integrator. Preparative vapor phase chromatography was carried out on a Varian aerograph model 920 (thermal conductivity dectector) with a pyrex- lined injection port. Columns utilized were: 10'x 1) 3. stainless steel containing Pennwalt 223 amine packing (Applied Science Laboratories, Inc. ); 20' x 1/," stainless steel packed with 10% dibutyltetrachlorophthalate on 100-120 mesh chromosorb P(A/W, DMCS); 20' x 1) 3 stainless steel packed with 10% 7 , '-oxydipropionitrile on 100-120 mesh chromosorb P(A/W, DMCs); 6" x 1/4", and 10'x 4/4" glass, both packed with Pennwalt 223 amine packing; 10' x 3/ 3. aluminum, containing 25% é, fa '-oxydipropion- itrile on 60 80 mesh chromosorb P(A/W, DMCS). For preparative thin layer chromatography, thick silica gel plates (20 x 20cm, Merck) were employed. Pyrolytic procedures Vacuum line pyrolyses were carried out in a heated, evacuated, 23 (19 - 107° torr, Hg manometer) cylindrical pyrex chamber, diameter 2,8 cm, length 30 cm, total volume 185 cm®, Samples to be pyrolysed were introduced via syringe through a small rubber septum sealing the 0.6 cm x 2 cm injector at one end. The other end of the tube could be opened (stopcock) to an evacuated U-shaped trap, with an additional joint, and stopcock for distillation of samples into small tubes for analysis. The chamber was heated by a Hoskins type FD 203A tube furnace, controlled by a temperature controller. Temperature was measured with an iron- constantan thermocouple and potentiometer. In a typica! experiment, the System was evacuated, and the stopcocks to the line and to the chamber were then closed. A sample was injected into the chamber, then after a time (usually 5 or 30 seconds, sometimes longer) the pyrolysis tube was opened to the trap, cooled with liquid nitrogen. The sample was removed from the line by distillation into a small tube, which was sealed and re- moved. The distillate was frozen in the bottom of the tube, broken open, capped with a serum stopper (sometimes additional solvent was added), and on melting, injected into the inlet of an analytical VPC. Tne base-inducec decompositions were carried out in base-washed, oven-dried pyrex tudes (1.2 x 8.0 cm, joint to $ 14/35 male joint, joined tc 0.6 x 4.0 cm tube, for degassing and sealing). A solution of the sub- strate in distilled, degassed diglyme (bubbling nitrogen through the diglyme is aot Sufficient, but two ox three freeze-thaw cycles, preceded by pumping oirectly on the liquid to remove a trace low-boiling contaminant, is satis- factory; was frozen (77K) under nitrogen in the tube. To this, a solution of the base to be used (usually 2N sodium n-butoxyethoxide in n-butoxy- ethanol, prepared by stirring 1-outoxyethanol, freshly distilled from sodium $8 => y 3 > 24 with two equivalents of freshly cut sodium metal for several hours at or below room temperature, 0.1 to 9.2 ml) was added via syringe, and frozen almost immediately. The tube was purged with nitrogen, and sealed with a torch. After the tube was warmed to the desired temperature (and shaken soon after liquification to insure adequate mixing) for a certain time, it was again frozen with liquid nitrogen, the top scored with a triangular file and broken, and volatile products distilled (high vacuum, at room temperature), then distilled again, into a small tube (as before) which was sealed and analy das described above. The oxidation experiments were carried out on the vacuum line. A weighed portion of the oxidant (manganese dioxide or mercuric oxide) was carefully degassed (these solids tend to leap out of the tube and con- taminate the rest of the line if evacuated too quickly) in a base-washed, oven-dried tube placed on an auxiliary manifold, protected by stopcock. A solution of volatile aminoaziridine in n-hexane (purified by preparative VPC on 20' x 3/ 3" aluminum column packed with 2, ('-oxydipropion- itriie)} was placed ina tube on the same auxiliary manifold, degassed (freeze- thaw method), and distilled onto the degassed oxidant. The tube was closed off, the liquid nitrogen dewar removed, and either replaced with a dewar filled with ice water, or ambient air for a time, then the reaction tube was opened to the evacuated manifold open to another tube at 77K. The dis- tiliste was analy ed by VPC. a — ‘ : 0 Preparation of Meso-2, 3-dimethanesulfonyloxy butane A solution of meso~2, 3-butanediol (27.0 g, 6.3 moles, 98% RIC/ROC} s in 150 mi dry pyridine was placed in a dry flask under argon equipped with The solution was maintained close to the freezing point of pyridine 25 (-42°) with a dry ice-acetone bath. Methanesulfonyl chloride (47.5 ml, 0.614 moles, Aldrich, distilled from P,O,) was added slowly from a pressure equalizing addition funnel over a period of 1.5 hours. The resulting brownish semi-solid was allowed to warm to room temperature, and stand 0.5 hours. After adding 20 ml distilled water the mixture was poured onto ca_ 300 g curshed ice. When the ice had melted the crystals were collected on a coarse glass frit and washed with two 50 ml aqueous sodium chloride, dried (MgSO,), and solvent removed under reduced pressure. One recrystallization from absolute methanol gave 53 g (72%) white crystals, mp 64-7°. NMR(CDCI,): 1.25-1.55 (m, 6H, sharp peaks at 1.37, 1.48), 3.08 (s, 6H), 4.65-5.10 (m, 2H); IR(CCl,); 3035 (w), 2995(w), 2945 (w), 1360 (broad), 1155 (s), 1075 (w), 995 (w), 970 (m), 940 (m), 905 (m). Preparation of 1~Amino-2, 3-cis ~dimethylaziridine® In a 100 mi base-washed round-bottomed flask, fitted with serum stop- ner, reilix condenser, magnetic stirrer and argon inlet, was placed 25.6 ¢ (0.1 mole) meso~-2, 3-dimethanesulfonyloxybutane. The system was flushed with argon. To this anhydrous hydrazine (21 ml, 0.658 moles, 97% MCB) and hydrazine hydrate (20 ml, 0.412 moles) were added by syringe. The mixture was allowed to stir and maintained at 58-60° (silicone oil bath, preheated to 65°) for four hours. Upon cooling two vhases were evident. The reflux condenser was replaced by a short vath distillation apparatus ‘pase washed. oven dried), Avproximately 20 m! of colorless distillate was collected (to 70° at 125 mm) ina reciever containing a KOH pellet, and cooled by dry ice-aretone. Solid KOH (2.0 ¢, total) was added portion 26 wise to the distillate, and this was shaken to effect solution. After standing ca o minutes the clear, colorless lighter phase was drawn off (double- ended needle) and stored over a few KOH pellets under inert atmosphere in the freezer while preparative VPC was in progress. The aminoaziridine was prepped on a 5' x 1/ 4" glass column packed with Pennwalt 223 (Applied Science Laboratories), oven temperature, 110°; injector and detector 160-180°. That slight decomposition to butenes occured under these conditions was confirmed by analytical v.p.c. with the injector off (25-30°). NMR (CDCI,): 1.0-1.2 (dd, J's = 1.5, 4 cps; 6H), 1.4-2.0 (m, 2H), 3.6-3.75 (broad 5, 2H); IR (CCL): 3300 (m, b), 3250 (m), 3150 (m), 2990 (heat) (sh, m), 2950 (m), 2920 (m), 2970 (w), 1590 (m, b), 1460 (m), 1405 (s), 1380 (s), 1140, 1070, 1010, 950, 750. Other components of the distillate could be observed. One, relative retention with respect to 1-amino-cis-2, 3-dimethylaziridine of 1.51 on Pennwalt, was isolated and tentatively identified (nmr, ir) as 3-hydrazinobut- 1-ene. NMR (CDCL): 1.14 (d, J= 7, 3H), 2.98 (s, overlapping), 3. 0-3. 47 im; J= 7, peaks at 3.10, 3.22, 3.33; overlapping multiplets, total overlap- ping = 4H); IR (meat): 3255 (b, m), 3175 (w), 3055 (w), 2968 (m), 2917 (m), 2855 (w), 2810 (w), 1625 Gv}, 1595 (w), 1440 (w), 1405 (m), 1375 (m), 1315 (w), 1250 (w), 1105 (m), 1085 (m}, 983 (m), 910 (s), 840 (w). A different peak, with relative retention (as above) of 1.75 was prepped twice on Pennwalt. NMR and IR (below) suggest that this compound could be cis-3,4-dimethyl-1, 2-diazacyclobutane. An NMR experiment was performed which consisted of bubbling O, through a solution of this compound in an NMR tube, then measuring its NMR spectrum. A new, strong Singlet was observed at 2.13. NMR (CDCi,): 1.00-1.25 (m, sharp peaks at 1.07, 1.17, appearance similer to the cis aminoaziridine methyls 27 1, 93-2.23 (m); IR(@meat): 3250-3350 (m), 2960 (s), 2927 (m), 2875 (m), 1610 (w, b), 1560 (m), 1375 (m), 1188 (w), 1150 (w), 1090 (w), 999 (w), 943 {m), 920 (m), 780 (w). Preparation of 1-Methane sulfonamido-cis-2, 3 ~dimethylaziridine!* A solution of 1-amino-cis-2,3-dimethyl aziridine (100 mg, 1.16 mmoles, purified by pype on Pennwalt to 2 99.7% isomeric purity) and triethylamine (120 mg, 1.19 mmoles, distilled from CaH,, stored over KOH in stoppered flask in a dessicator) in 2 m! methylene chloride ‘passed through alumina) was stirred in a dry flask under argon at -78°. Methanesulfonyl chloride (85 #1, 1.11 mmoles, distilled from P.O, and stored in a dessicator) was added drop wise from a syringe over 3 minutes. Tne reaction mixture was allowed to stir 20 minutes at -78°. The bath was removed and stirring continued for 35 minutes. Dilution with 3 ml methylene chloride was followed by washing with 3 ml saturated aqueous NaHCO,, withdrawal of the organic phase by syringe, filtration through MzSO, and slass woo!. The reaction mixture was concentrated umder reduced pressure at 25°, to afford 220 mg slightly yellow solid. Recrystallization from Low Doiling petroleum ether/benzene gave 82 mg product, mp 74-7°, second crop, 18 mg, 68-74°. Total yield 100 mg (52%). An attempt to sublime 22 mg (first cron) at 0.05-0.02 mm and 0-70° onto a cold finger at -78° gave 2 mg white solid, mp 79 80°. NMR (CDCl): 1.05-1.25 (m, 6H, sharp osake af 1.0, 2.18), 2.0-9.4 (0 28), 3.10 (s, 8H) 5.3-5.9 (broad, 1H): PR (CCL: S290 tw, 8220 Se, bj, S030 fw}, 2979 (wi, 2935 Gv), 1715 Ow), i450 fw), 1410 ow), 1365 ¢s), 1345 (s}, 13820 (s), 1255 (w), 1155 (s), 960 (m}, 976 tm}: M.S: 164 (P*., 85, 7 75 83, 55, 56, 42, 41, 39. Preparation of L-p-roluenesu.toramico- vis-2, 3-dimethylaziridine 28 To a stirred solution of l-amino-cis-2, 3-dimethylaziridine (100 mg, 1,16 mmoles purified by vpc) and triethylamine (118 mg, 1.17 mmoles) in 2 mi methylene chloride, maintained at -78° (dry ice/acetone) under N2, was added via syringe a solution of p-toluenesulfonyl chloride (220 mg, 1.15 mmoles; recrystallized from chloroform-petroleum ether (35-60)) in 1.0 ml methylene chloride over a period of five minutes. The reaction mixture was allowed to stir for one hour at -78°, and 1.5 hours at room temperature. The reaction mixture was taken up in 3 ml methylene chloride. This was washed three times with 50 ml aqueous sodium chloride, dried (Na,sQ,) and concentrated under reduced pressure to afford 60 mg light yellow solid, mp 80-2°. Speciral samples were obtained by preparative t.l.¢. (silica gel). NMR (CDCI,): 0.9-1.25 (m, 6H, sharp peaks 0.95, 1.06) 1.9-2.3 (m, 2H), 2.43 (s, 3H), 6.0 (broad, 1H), 7.58 (m, 4H, para substituted aromatic 7.92, 7.78, 7.38, 7.23); IR (CCL): 3230 (w), 3190 (w, b), 2950 (sh), 2915 (m), 2864 (m), 1596 (w), 1485 (w), 1446 (w), 1395 (w}, 1373 Gn}, 1241 (m}, 1825 (m), 1301 (w), 1286 (w), 1195 (w), 1130 (w), i167 (s), 1100 ni, 1039 Gm), 1015 (w); MS: 273 (from decompcsition, CyESSOoC 7Hn), no peak at 240. Preparation of D(-}-2, 3-dimethanesulfonyioxybutane A magnetically stirred solution of D(-)-2,3-butanediol (27.0 g, 0.3 moles, Burdick and Jackson, lot 6995} in 225 ml dry pyridine was cooled oh 3, Ory nue-acetone path mti freezing was observed on the wall of the mS nee ee re wwing tT Eee mia Deeg py PEPE FY. 7” gra sat YY Ase tt lia _ i Methanosulforny: chieri¢e (75 6 ¢. 653 moles) distillec from i &, Po, Was adden Grogwiss over 2n sour with cooling as necessary. Cooling and stirring were continues ovo sours. then allowed to warm up and stir four aours, The regating tnics vhite precipitate wes filtered on a coarse 29 glass frit, washed with 50 ml distilled water. Water was removed under aspirator pressure. The crude product was taken up in 800 ml methylene chloride. This was washed with water, dried (MgSO,) and concentrated to afford 64.0 g (86%) colorless crystals, mp 123-5°. NMR (CDCl): 1.30-1.55 (m, 6H, peaks at 1.41, 1.52), 3.07 (s, 6H), 4.5-4.9 (m, 2H); IR (CCl1,): 3018 (m), 2980 (m), 2926 (w), 1438 (w, b), 1407 (w), 1355 (s), 1340 (s), 1225 (w, b), 1173 (s), 1072 (m), 1020 (m), 968 (s), 934 (s), 904 (s), 854 (m). Preparation of 1-Amino-trans-2, 3 -dimethylaziridine® In a 100 ml round-bottomed flask equipped with reflux condenser, magnetic stirbar and nitrogen inlet, was placed 15.0 g (0.061 moles) of d-(-)-2,3-dimethanesulfonyloxybutane. The addition of 15.0 ml (0.47 moles) of anhydrous hydrazine and 15.0 ml (0.31 moles) of hydrazine hydrate was followed by heating for 40 hours at 40°. The reflux condenser was replaced by a short path still head, and distillate collected up to 70° at 110 mm (vacuum pump, controlled nitrogen leak). The distilled material was saturated with KOH (reagent grade), the top layer withdrawn by syringe and distilled again. Distillation at 25° on the vacuum line (1074-107° torr) gave 1.0 g product (vpe isomeric purity Z99.5%). Attempts to purify this material by preparative vpc on Pennwalt 223 under a variety of con- ditions were frustrated by the increasing conversion of this material to a compound with relative retention 1.31 to the desired compound. Retention data suggests that the impurity is the previously isolated 3-hydrazino-but-1-ene. NMR (CDC1,): 1.05-1.80 (m, 8H), overlapping methine and methyl signals peaks at 1.13, 1.18, 1.23, 1.24, 1.36), 3.09 (broad, 2H); IR (CCl,): 3330 (b), 2930 (s), 2948 (s), 2916 (s), 2860 (m), 1585 (m), 1453 (m), 1380 (m), 1322 (w), 1118 (w), 1083 (w), 1020 (m), 963 30 (w), 925 (m} MS: 86 (P"), 71, 59, 56, 55, 44, 42, 41, 34, 32, 29, 28, 27 higher mass peaks (low intensity at 91, 97, 120, 135, 150 (150 may be due to the allylic mesylate). Attempted preparation of 1-Methanesulfonamido-trans-2, 3-dimethylaziridine To a cooled (-78°), stirred solution of 1-amino-trans-2, 3-dimethyl- aziridine (53 mg, 0.617 mmoles) and triethylamine (62 mg, 0.614 mmoles) in 1.5 ml methylene chloride (passed thra gh Activity grade 1 Alumina), was added methanesulfonyl chloride (67 mg, 0.588 mmoles, distilled from P,O;) dropwise. This was allowed to stir 1.5 hours the yellow solution was allowed to warm to 25°. One ml methylene chloride, and one ml saturated NaHCO, solution were added. The organic phase was drawn off after a few minutes of stirring, concnetrated under reduced pressure at 25°, and the yellow oil taken up in 0.5 ml CDCL, (passed through alumina) with ca 1% TMS. The nmr spectrum was complicated, but running several spectra showed the products to be unstable to these conditions. The half- life for decomposition (by following the sulfonyl methyl signal at 3.136 ) was about one hour. The infrared spectra and hot-tube decompositions were run on samples prepared as above, but not subjected to the nmr probe, yields were 35-45%. The material could not be crystallized. IR (neat): 3265 (m), 3217 (m), 2980 (m), 2930 (m), 2870 (w), 1625 (w, b), 1450 (m), i378 (m), 1322 (s), 1151 (s), 1029 (m), 980 (m), 965 (m), 843 (w), 795 (re), 775 (m). Preparation of 1-p-‘Toluenesulfonamido-trans-2, 3-dimethylaziridine 4 soluticn of p-toluenesulfonylchloride (203 mg, 1.06 mmoles, re- crystallized in 20 mi dry methylene chloride was added over 10 minutes to a etirred solution of l-amino-trans-2,3-dimethylaziridine (95 mg, 1.10 31 mmoles) and triethylamine (148 pl , 1.06 mmoles) at 0°. The reaction was stirred 2 hours at 0°, and 1 hour at 25°. This was concentrated under reduced pressure, and the remaining solid extracted with 3 x 5 ml ether. The ether soluble material was redissolved in 20 ml 5:1 ether/methylene chloride, washed with two protions aqueous sodium chloride, dried (MgSO,), and concentrated. Impurities were precipitated from benzene with hexane, and the soluble fraction was recrystallized from benzene to give 60 mg light yellow solid, mp 98-100 (dec, yellow melt). Further purification by thin layer chromatography was achieved, at 50-60% re- covery. NMR (CDCL,): 1.00-1.17 (m, 3H, peaks at 1.03, 1.13) 1. 46-1. 67 (m, 3H peaks at 1.48, 1.59), 1.45 (s, 3H) 3.40 (broad, 2H) 3.87-4.25 (m, 2H), 7.57 (m, 4H, aromatic A,B,, J, = 9, J, = 25, peaks at 7.85, 7.70, 7.43, 7.28, 7.30); IR (CCL): 2720-2990 (w, b), 1595 (w), 1443 (w), 1372 (w), 1350 (m, b), 1300 (w), 1285 (w), 1180 (w), 1164 (s), 1089 (w), 1076 (w), 1014 (w), 840 (w). | Preparation of 1-Phthalimido-trans-2, 3-dimethylaziridine!> Trans-2-butene (5 ml at -78, K and K) was distilled into a stirred, cooled (-78) suspension of N-aminophthalimide (prepared from hydrazine and phthalimide! ?, also available from Aldrich) in 50 ml methylene chloride (distilled from P,O,) via a dewar condenser. Lead tetraacetate (4.22 g, 9.53 mmoles, Matheson, Coleman and Bell) was added in four portions over 40 minutes, after which the cold bath was removed and stirring con- tinued. After 1.5 hours the reaction mixture was filtered through celite, then two inches of silica gel. This was concentrated under reduced pressure to give a cloudy yellow oil. Trituration with small volumes of methylene chloride and filtration, followed by solvent removal gave 1.1¢ crude oroduct, Column chromatography on 22 ¢ silica gel with diethyl ether/low 32 boiling petroleum ether (1:9) gave 385 mg (19%) yellow oil, which solidified to a yellow solid, mp 65-77 NMR(CDCI,): 1.2-1.6 (dd, J = 7, peaks at 1.27, 1.37,1.38, 1.48), 2.2-3.0 (m, 2H, overlapping multiplets, peaks at 2.25, 2.35, 2.45, 2.53,2.59, 2.63, 2.78, 2.87, 2.96), 7.77 (s, b, 4H): IR (CHCL): 3030 (m, sh), 3010 (m, sh), 2975 (m), 2935 (m), 2880 (w), 1781 (m), 1761 (m), 1716 (vs), 1656 (w), 1604 (w), 1481 (m), 1438 (m), 1373 (s), 1356 (m), 1315 (m), 1213 (m, b), 1175 (m), 1133 (m), 1080 (m), 1022 (m), 970 (w), 950 (w), 890 (s), 844 (w). Preparation of 1-Phthalimido-cis-2, 3 -dimethylaziridine! Cis-2-butene (10 ml at -78, ca 5-fold excess, K + K Laboratories, Inc. ) was distilled into a dry 200 ml round-bottomed flask, containing N- aminophthalimide® (5.00 g, 30.8 mmoles) and 100 ml methylene chloride (distilled from CaH,). The system was flushed with argon, and lead tetra- acetate (13.79 g, 31.2 mmoles) was added over 45 minutes at -78 in small portions every few minutes. The reaction was stirred one hour at -78, 3.0 hours at room temperature, filtered through 1.5 inches of silica gel, then through 1.5 inches of neutral alumina. This was concentrated under reduced pressure. Extraction of the resulting semisolid with ether-petro- leum ether 35-60 (1:1) and concentration under reduced pressure gave 2.59 ¢ (39%) of product, sufficiently pure for further synthesis. A portion {400 mg) of this material chromatographed on 11 ¢ silica gel with ether- petroleum ether (1:9) melted at 93-95°. NMR (CDC1,): 1.25-1.55 (m, 6E, peaks at 1.33, 1.37, 1.40, 1.43), 2.4-2.85 (m, 2H), 7.68 (s, 4H); 1726 (s), 1711 fvs}, 1604 (wi, 1461 (m), 1448 (w), 1431 (w), 1403 (w), 1376 fs}, 1356 (m), 1323 (w), 1278 (w), 1210 (w, b), 1175 (m), 1150 Gm), 33 1097 (m), 1080 (m), 1067 (m), 1012 (m), 987 (m), 982 (m), 890 (s), 827 (w). Preparation of 1-Amino~cis-2, 3-dimethylaziridine from 1-Phthalimido- cis-2, 3-dimethylaziridine In a 50 ml base-washed, oven dried, round bottomed flask, fitted with a septum, was placed 1-phthalimido-cis-2,3-dimethylaziridine (2.19 g, 10.1 mmoles, crude-decomposes on chromatography). The flask was flushed with argon. Hydrazine hydrate (15 ml), was added by syringe. The reaction mixture was allowed to stand 1.5 hours, than allowed to stir 0.5 hours at 25°. Then 20 ml diethyl ether (distilled from sodium and benzophenone after refluxing the blue solution under inert atomosphere) was added via syringe. The mixture was allowed to stir a few minutes, and the ether layer was removed. Two more ether extractions (15, 10 ml) and distillation of the solvent from the combined ether layers gave ca_400 mg (about 45%) oil, which was further purified by preparative vpc on Pennwalt 223 (at 110°). Spectral and vpc retention data were identical to material prepared by another method. Net Stereochemistry of the Preparation of 1-Amino-cis-2, 3-dimethylaziridine from cis-2-butene In this vpe experiment chromatographed samples (ca_50 mg each) of 1-phthalimido-cis-and trans-2, 3-dimethylaziridine were each (separately) treated with hydrazine hydrate (0.6 m1) and extracted with 3 ml ether to provide authentic vpe samples. Also, crude 1-phthalimido-cis~2, 3-di- methylaziridine (56 g) was treated with hydrazine hydrate (10 ml), and extracted with 20 ml ether. VPC analysis of the extracts on Pennwalt 223 showed that the hydrazinolysis of the crude intermediate gave 1-amino- cis~2, 3-dimethylaziridine at least 99% isomerically pure. 34 Preparation of Methanesulfinylchloride The procedure followed is essentially that of Dougiass! 6, Methyldisulfide (47.1 ¢g, 0.5 moles, Aldrich) and glacial acetic acid (60.1 ¢, 1.0 mole) were weighed into a dry 500 ml three-neck round bottom flask, and allowed to stir with cooling (-78°). Chlorine (ca 80 ml at -78, 0.75 moles, Matheson gas products) was distilled from a 100 ml flask via a dewar condenser (~78) into the reaction flask, which was vented via a cold trap (-78), a back-up trap, and an aqueous NaOH bubbler. The reaction vessel was maintained at ca ~10 to -15 during the distillation ‘about 2 hours}, cooling was discontinued and stirring continued 1.5 hours. This was then heated to 35-37° with a flameless heat gun. The amber solution was distilled at 1 atm. (100° bath) affording ca 60 ml of distillate {mostly acetyl chloride). Distillation at aspirator pressure gave 60 ml of distillate boiling 40-50°. Redistillation, also at aspirator pressure (20 mm), through a 15 cm glass Vigreaux column gave (after a small fore- run) three fractions: 45-47°, 12 ml, light yellow; 47-48°, 25 ml, yellow: 48-50°, 8 mil, yellow. Preparation of Methanesulfinic Acid Methanesulfinic acid has been prepared by Cram and coworkers!®”, Methanesulfinyl chloride (2.0 g, 20.4 mmoles, bp 45-47” at 20 mm) was 2:lowed to stir ina dry 25 ml flask, with a side arm equipped with a septum, er nitrogen atmosphere. The temperature was maintained below -30°. Distilled water (0.36 mi, 20.9 mmoles) was added dropwise by syringe while oilvogen was oubbsed through the solution (to carry off the HCl generated). ‘ne addition took only 2 few minutes and nitrogen bubbling was continued an auditions: LU minutes below 0°. The solvent was removed at C° {2 hours), “4 & e woo Tigges wetted with nitrogen, and 16 ml ether was added. The twe phase 35 mixture was left to stand in the freezer a few days, whereupon long, thin needles formed. The yellow ethereal solution was removed by syringe, and the crystals washed with three 5 ml portions of pentane. Solvent was further removed under vacuum (0.1 mm) for several hours at 0°. This afforded 0.9 g (55%). Identification of Minor Products of the Pyrolysis of 1-Methanesulfon- amido-cis-2,3-dimethylaziridine by Gas Chromatography-Mass Spectroscopy The products of the previously described byrolysis of 1-methane- sulfonamido-cis-2, 3-dimethylaziridine at 310° in the hot tube were analysed by GC-MS for minor components by Mr. M. Keith Murphy of the J. L. Beauchamp research group on GC-MS system assembled by Mr. Jon Burke. Peaks examined and identified are listed in Table 8. Interestingly, when the chromatograph was observed only at m/e 64 a large, tailing peak was observed. The corresponding peak was also observed by monitoring only m/e 48 (64-16). This most likely corresponds to sulfur dioxide, resulting from thermal decomposition of the (presumed) byproduct methanesulfinic acid in the hot tube. Table 8. Time % _rrt_ assignment 1:59 4,4 0. 196 ethane 2:19 3.5 0.270 propene 3:21 1.4 0.396 1-butene 5:01 0.8 0. 618 C,H, (not further identified) 7:26 0.9 0. 895 trans ~2-pentene 8:11 0.7 1. 00 cis-2-pentene 36 Examination of the Thermal Decomposition of 1-Amino-trans-~2, 3-di- methylaziridine This experiment was carried out by Miss Francis Houle of the J. L. Beauchamp research group. The photoelectron spectrometer system has been described. In the gas phase, a degassed sample of 1- amino-trans-2, 3-dimethylaziridine was diluted with argon and passed over an electrically heated filament into the photoionization detection system. Products were assigned on the basis of their photoelectron spectra which were recorded at filament temperatures, from 416°-655°C. The major products observed were trans-2~-butene (small proprtions of cis-2-butene would not have been distinguishable) and molecular nitrogen. A small (ca 5% with respect to the nitrogen signals) amount of molecular hydrogen was also observable. No hydrazine or ammonia were detected. The fate of the rest of the hydrogen is not known. It was suggested that a piece of tantalum in the detector may have interfered with this experiment. 37 Refere! ferences 1 (a) D. M. Lemal in "Nitrenes", W. LWowski, Ed., Interscience, New York, N. Y., 1970, Chapter 10; (b) B. V. Ioffe and M. A. Kuznetsov, Russ. Chem. Rev Rev., An "131 (1972). 2. (a) C.G. Oe pereas Chem. Soc. 1943 1983); (ob) P. ’B. Dervan and T. Yehara, J. Amér. Chem. Soc., 98, yas (1976). 3. J. P. Freeman, D. G. Pucci, and G. H. Binosh, J. Org. Chem., 37, 1894 (1972). ——— 4. 4 3) and W. H. Graham, J. Amer. Chem. Soc., 89, 1761 1969). en 3. (i970) Carpino and R. K. Kirkley,J. Amer. Chem. Soc., 92, 1784 0). ~~ ~~ Oo ® D. Felix, R. K. Muller, U. Horn, R. Joos, J. Schreiber, and A. Eschenmoser, Helv., 55, 1276 (1972). 7. R. B. Woodward and R. Hoffman, ''The Conservation of Orbital Symmetry", Academic Press, New York, New York, 1970. 8. J. E. Baldwin, G. Hofle, andS. C. Choi, J. Amer. Chem. Soc., 93, 2810 (1971). 9. R. D. Clark and G. K. Helmkamp, J. Org. Chem., 29, 1316 (1964). 10. N. P. Neureiter, J. Amer. Chem. Soc., 88, 558 (1966). 11. F. G. Bordwell, J. M. Williams, Jr., E. B. Hoyt, Jr., and B. B. Jarvis, J. Amer. Chem. Soc., 90, 429 (1968). 12. M. H. Akhtar and A. C. Oehschlager, Tetrahedron, 26, 3245 (1970). 13. J. E. Baldwin, A. K. Bhatnagar, S. C. Choi, and T. J. Shortridge, J, Amer. Chem. Soc., 93, 4082 (1971). 14. T. Uyehara, "Research Report V", August, 1975. 15. D. J. Anderson, T. L. Gilchrist, D. C. Horwell, and C. W. Rees, Jd. Chem. Soc. (Cc), 576 (1970). 6. (aj) J. B. Dou as B. S. Farah, and E. G. Thomas, i Org. Chem. , 26, 1996 (1961 F. Wudl, D. "A. Lightner, and D. J. Crari, J. Khor, Chom, Son, 89, 4099 (1987). i7. T. W. Gibson and P. Strassburger, J. Org. Chem., 41, 791 (1976). is. J. L. Kice, G. Guaraidi, and C. G. Venier, J. Org. Chem., 31, 3561 (1966). AoaRL MOE NS 19, 20, 21, 38 H. D. K. Drew and H. H. Hatt, J. Chem. Soc. (C), 16 (1961). H BD. C. Frost, 8. T. Lee, C. A. McDowell and N. P. C. Westwood, - R. Hoffman, C. 95, 629 (1973). ~ fF, Chem, Phys., 64, 4719 (1976). C. Levin, and R. A. Moss, J. Amer. Chem. Soc., 39 Appendix: Derivation for Scheme 3. Definitions: [X] = concentration of species X A= (tal B= [ib] C= (1'a] D= [1'p] E= Bal F = [8b] o = (r/i) cis = (E/F) cis 2 = (r/i) trans = (F/E) trans Ri= k,/k, Ra= ky/k, Equations: From A (la): = k,C-k,D~k,D=90 (steady state) t at from (1) k,C D= —~— k, + k, from (2) dt kk, (1) (2) (3) (4) The solution of this differential equation (4) consists of two terms, aa exponential part, and a time independent part. For non-zero time the 40 exponential rapidly approaches zero, and C approaches from (3) and (5) k, kA - (kik, + kk, + kky) from (vii), (5) and (6). k, . (k, + k,) = aE + ( k,C k,D kK, k, (Ky D = ol = rearranging (7) (Ry + 1) By a similar sequence for B, from (9) and (10), oe = d = k,D -k,C -k,C = 0 AD. kB +k,C -kD- kD dt equation (11), analogous to (8) is obtained: p _ (= + ) = R(R, +1) Ky a steady state value: (5) (6) (7) (8) (9) (10) (11) Equations (8) and (11) are simultaneously solved for R, and R, in terms - of and to give equations (12) and (13): R = af-1 ' 1 +1 . a3- 1 R = se aAt+l1 (12) (13)