摘要:
Chemical Com m u n i cat ions NUMBER 17/1968 4 SEPTEMBER Nonplanar Cyclobutane: Dearnination of 3-Ethoxycyclobutylamine By IRVING LILLIEN (Department of Chemistry, Marshall University, Huntington, West Vi&nia 25701) CARBONIUM ION REACTIONS of cyclobutane and cyclopropylmethyl derivatives have been charac- terized in terms of nonclassical bicyclobutonium ions functioning as common intermediates.' Recently, however, a number of cyclopropyl- methyl reactions have been shown to involve unrearranged cyclopropylmethyl cations rather than bicyclobutonium ions.2 We have interpreted the amine deaminations and $-bromobenzene- sulphonate solvolysis4 of derivatives of the cis- and trans-isomers of the 3-isopropylcyclobutyl system in terms of conformationally-controlled reactions involving classical intermediates.In related work, we have examined the deamination of 3-ethoxy- cyclobutylamine. We report that, unlike 3-alkyl- substituted cyclobutylamines, this compound gives 86% of unrearranged cyclobutane. Synthesis was accomplished by conventional base-catalysed condensation of a 2-ethoxy- 1 , 3- dihalogenopropane with malonic ester in 20-30% yield, followed by hydrolysis, decarboxylation, and a Schmidt reaction. The amine consisted of approximately 58% trans- and 42% cis-product, by V.P.C. and n.m.r. analysis). The proton geminal to the NH, gives a multiplet centred at 4.5 p.p.m. (trans) or 3.5 (cis) (60 MHz). Deamination was carried out in conventional fashion in glacial acid That this reaction does not involve bicyclo- butonium intermediates may be readily ap- prehended from the failure of the concept of the electrically-most-stabilized ion6 (I) to explain its course.This ion, involving donor participation by an ethoxy-group, must clearly lead to different products. It appears instead that the course of the reaction is determined by nucleophilic com- petition of the ethoxy-group with ring-bond migration: resulting in the probable transition state (11) analogous to (111). Such neighbouring-group containing a trace of acetic anhydride. In addition to 86% of a mixture of approximately 59% trans- participation across the short (< 2 A) transannular and 4 1 yo cis-3-ethoxycyclobutyl acetate, there was distance sufficiently stabilizes the charge accum- obtained 14% of side products predominantly ulating on the ring so that rearrangement is composed of a straight-chain unsaturated acetate, minimal.These results support the original sug- as yet unidentified. Ethyl alcohol was also obtained gestion that similar hydroxy-participation may be in the reaction. responsible for trans-rate-acceleration in the lo091010 CHEMICAL COMMUNICATIONS, 1968 isomeric 3-hydro~y-2~2~4~4- toluene-p-sulphonates.6 The present results are tetramethylcyclobuty1 analogous to those reported for the deamination of 3-benzyloxycyclo- butylamine several years ago,' in which the corresponding cyclobutanol and benzyl alcohol were obtained. It is now evident, however, that no special aromatic effect is involved, but that the presence of an alkoxy-group is sufficient to divert a predominant amount of diazonium intermediate to unrearranged products.Further, the complete absence of cyclopropane products, reported by these authors, is now confirmed in the present work by n.m.r. Implicit in the present suggestions is expectation of some discrimination between cis- and trans- amines, since it is thought that backside trans- ethoxy-participation would be preferred in forma- tion of (11). (Received, March 15th, 1968; Corn. 327.) R. H. Mazur, W. N. White, D. A. Semenov, C. C. Lee, M. S. Silver, and J. D. Roberts, J . Amer. Chem. SOC., 1959, 81,4390; J. D. Roberts and R. H. Mazur, J . Amer. Chem. SOC., 1951,73,2509,3542. P. von R. Schleyer and G. W. Van Dine, J . Amer. Chem. Soc., 1966,88, 2321; M. Vogel and J. D. Roberts, ibid., 2262; H. G. Richey, jun., and J. M. Richey, ibid., 4971; H. L. Goeringand K. E. Rubinstein, Abstracts, 151st. National Meeting of the Amer. Chem. SOC., Pittsburgh, March, 1966, p. 11K. 8 I. Lillien and R. A. Doughty, Tetrahedron Letters, 1967, 3953. 4 I. Lillien, G. F. Reynolds, and L. Handloser, submitted for publication. 6 R. H. Hasek, R. D. Clark, and J. H. Chaudet, J. Org. Chem., 1961,26, 3130. 7 M. Maxim, M. Avram, and C . D. Nenitzescu, Acad. Reports Pop. Romfne, Studii Cercetdri Chim., 1960, 8, 187. M. S. Silver, M. C . Caserio, H. E. Rice, and J. D. Roberts, J . Amer. Chem. SOL, 1961,83, 3671.
ISSN:0009-241X
DOI:10.1039/C19680001009
出版商:RSC
年代:1968
数据来源: RSC