Anti versus Syn Opening of Epoxides Derived from 9-(3-Deoxy-β-<scp>d</scp>-<i>g</i><i>lycero</i>-pent-3-enofuranosyl)adenine with Me₃Al: Factors Controlling the Stereoselectivity

Abstract

Upon epoxidation with dimethyldioxirane, the 2',5'-bis-O-silyl derivatives of 9-(3-deoxy-beta-D-glycero-pent-3-enofuranosyl)adenine gave the respective "3',4'-up" epoxides exclusively. Reaction between these epoxides and Me3Al was investigated in detail. It was found that the stereoselectivity of epoxide ring opening (anti versus syn) varied significantly upon changing the amount of Me3Al, the solvent, the O-silyl protecting group, and the reaction temperature. A possible reaction mechanism is proposed.