Acta Chimica 65. (1970)
4. szám - ORGANIC CHEMISTRY - Bernáth G.–Kovács K.–Láng K. L.: Stereochemical Studies, VIlI.
Acta Chimica Academiae Scienliarum Iliingaricae, Tomus 65 (4), pp. 347—366 (1970) STEREOCHEMICAL STUDIES, VIII* CYCLIC AMINOALCOIIOLS AND RELATED COMPOUNDS, II N—О ACYL MIGRATIONS IN CIS- AND TR/1NS-2-AMINOMETHYLCYCLOIIEXANOL AND CIS- AND 77i4N'S-2-IIYDROXYMETHYLCYCLOIIEXYLAMINE DERIVATIVES** G. Bernáth, K. Kovács and K. L. Láng*** (Institute of Organic Chemistry, A. József University, Szeged) Received June 21, 1968 The kinetics of N—►O acyl migration of the N-benzoyl, N-p-methylbenzoyl, and N-p-nitrobenzoyl derivatives of cis- and ir<ms-2-aminomethylcyclohexanol and cis- and írans-2-hydroxymethylcyclohexylamine have been studied. The reactions were run in absolute dioxan in the presence of an excess of 0.5 mole of HC1. Measurements were performed at 2—4 temperatures for each compound in the range 70—112.3 “C.The second order rate constants, as well as the energies and entropies of activation are given. Trans isomers react faster than cis isomers. In the case of identical configurations, the N—»0 acyl migration of the 2-hydroxymethylcyclohexylamine derivatives is faster than that of 2-aminomethylcyclohexanol derivatives. Para substituents in the acylating benzoyl group decrease the rate in the order CH3—, H—, —N02. The reaction mechanism is discussed and compared with the results of earlier studies on 1,2- and 1,3-N—O acyl migrations. The formation of a bicyclic intermediate is regarded as the rate determining step. Introduction In the present series of papers a few stereospecific reactions of cyclic aminoalcohols are described. Cis- and trans-1,3- and 1,4-aminoalcohols and their derivatives, prepared hy stereospecific syntheses, containing the functional groups in 1,2-position on the common-membered alicyclic rings, have been used as models in the majority of cases. A comparative kinetic study of the above derivatives, as well as that of the corresponding reactions involving the analogous 1,2-aminoalcohols, serves the purpose of elucidating the detailed reaction mechanisms and providing information about the energetics of the bicyclic transition states. The compounds under consideration, and their homologues, are useful models for studying the connection between chemical structure and pharmacological effect. In the present paper we report kinetic studies on the acyl group migration in N-benzoyl- and p-substituted N-benzoyl derivatives of cis- and trans- 2-aminomethylcyclohexanol and cis- and írans-2-hydroxymethylcyclohexylamine. The stereospecific syntheses of the model compounds have been described [1]. Some features of their 1,3-N—>0 acyl migration reactions have been reported in preliminary communications [2—4]. * Part YII (I): G. Bernáth, K. Kovács, and K. L. Läng, Acta Chim. Acad. Sei. Hung. 64, 183 (1970) ** Preliminary communication: G. IÎERNÂTn, К. Kovács, and K. L. Láng, Tetrahedron Letters 1968, 2713 *** Dedicated to the 70th birthday of Prof. V. Bruckner. Acta Chim. Acad. Sei. Hung. 65, 1970 1*