Stephen K. Taylor

An efficient asymmetric synthesis of key intermediates in the synthesis of aphanorphine and eptazocine

Efficient, formal syntheses of aphanorphine and eptazocine are reported that involve epoxide cyclizations. The necessary chiral epoxides were prepared following treatment of diols prepared by Sharpless asymmetric osmylations of an alkene. The cyclizations formed a ring compound with the same enantiomeric purity as the starting epoxide.

The synthesis of three important lactones via an enzymatic resolution strategy that improves ee's and yields

Abstract Three important lactones have been synthesized in high enantiomeric purity by a complimentary, two-enantioselective-step strategy. In this approach, an enzymatic kinetic resolution is performed on a starting material that has been enriched in the faster-reacting enantiomer by an earlier enantioselective step. The results show that percent conversions, yields and ees can be dramatically increased by this complimentary approach, and they illustrate how modestly enantioselective techniques can be combined with kinetic resolution procedures to yield optically pure compounds. The utility of many modestly enantioselective (and hence sometimes disregarded) techniques can be enhanced thereby.

Efficient Preparation of γ-Hydroxynitriles via Nitrile Enolate-Epoxide Reactions: Scope and Diastereoselectivity

Abstract The nucleophilic opening of epoxides by nitrile enolates using an efficient, convenient protocol is described. The diastereoselectivity of this reaction was explored and found to give syn:anti ratios ranging from 1.1:1.0 to 4.8:1.0. ‡ Camille and Henry Dreyfus Scholar/Fellow 1995–1997.

Cyclizations wherein an epoxide acts as the source of initiation and termination steps. Evidence for an early transition state in biomimetic epoxide cyclizations

Abstract Epoxides which can competitively cyclize to either a double bond or aromatic group undergo novel bicyclizations where an epoxide is the source of initiating and terminating groups. The results suggest that biomimetic epoxide cyclizations involve early transition states.

A FACILE, HIGH YIELD SYNTHESIS OF γ- AND δ-HYDROXYAMIDES

γ- and δ-Hydroxyamides can be prepared in high yields by heating a lactone with ammonia in a pressure tube. The ammonia can be removed by controlled evaporation with ice/acetone cooling.