Configuration of Diastereoisomeric 2-Amino Cyclohexanols and a suggested mechanism for Acyl migration N-O. [antikvár]

CONFIGURATION OF DIASTEREOISOMERIC 2-AMINO CYCLOHEXANOLS AND A SUGGESTED MECHANISM FOR ACYL MIGRATION N ^ O. gábor fodor and j. kiss. (Institute of organic Chemistry of the University of Szeged). * Received 6. IV. 1950. In a recent communication (1) the separation of several arylaliphatic diastereoisomeric amino alcohols was reported, use being made of the difference in the behavior of the acylated derivatives towards alcoholic hydrogen chloride. This difference appears to be due to restricted rotation (2), which is also supported by model calculations (3). According to current opinion, neighboring groups can preferably participate in such reactions through formation of cyclic intermediates (4, 5). Bretschneider and co-workers (6) came recently to the same conclusions on different experimental results in the ephedrine series, and are also of the opinion that in the ephedrines the OH and NH groups are probably in trans, in y-ephedrines in cis positions, respectively. Similarly to our results concerning the acyl migration reaction, Pollak and Curtin (7) have recently observed marked stereospecificity in the diazotation reactions of some diastereoisomeric amino alcohols. We extended our investigations to derivatives of diastereoisomeric alicyclic amino alcohols, expecting that occurence of a similar stereospecificity in acyl migration reaction would supply information regarding the cis or trans position of the acylamido and the hydroxyl group relative to each other. We started with acylated 2-amino-cyclohexanols (19) which appeared to be all the more desirable as no acyl migration is known in this series (8). Also, the configuration of 2-amino-cyclohexanols was not yet brought (9) into genetic correlation with 1,2-cyclohexanediols of known configuration (10). Recently, however, (11) Mac Casland and co-workers found that 2-benzamido-cyclohexanol, m. p. 174° behaves in tosylation and subsequent detosylation analogously to trans- acetyl-cyclohexanediol-1,2 (12) and suggested — at variance with earlier considerations (13) — trans configuration for this amide, and a cis configuration for the diastereoisomeric (Il/a) amide, m. p. 189°. We tried to approach the problem from a new angle. In our experiments the cis and the trans forms of 2-benzamido cyclohexanol was treated with absolute alcoholic hydrogen chloride at room temperature under strictly iden-