Face selection in the reduction of p,p'-disubstituted 5,7-diphenyl-2-adamantanones and hydrolysis of the corresponding 2-adamantyl tosylates
作者:In H. Song、William J. le Noble
DOI:10.1021/jo00080a012
日期:1994.1
The reduction of 5,7-diphenyl-2-adamantanone with sodium borohydride in 2-propanol is affected by the introduction of a p-nitro substituent in one of the rings: the E-alcohol is obtained in small but easily measurable excess of 1.30:1. Conversely, the introduction of a p-amino group leads to an excess of Z-isomer by roughly the same factor (1.28). When both substituents are present, they evidently cooperate to produce a ratio of 1.64. The tosylates of the alcohols were prepared and their solvolysis rates measured in 3% aqueous hexafluoro-2-propanol and compared with those of the parent and p-substituted 5-phenyl-2-adamantyl tosylates. Additivity of substituent effects was again observed, but the p-aminophenyl group in these reactions was deactivating compared to phenyl, presumably due to II-bonding and/or protonation of the amino group in the acidic medium.