Electrophile‐induced cyclizations of silyl‐substituted 4‐alken‐1‐ols

Silyl‐substituted 4‐alken‐1‐ols cyclize in the presence of a wide range of electrophilic reagents to give substituted tetra‐hydrofurans. The silyl group accelerates ring closure by its β‐effect and its position determines the efficiency of stereo‐control. Thus, a vinylic silyl group as in 1, 3‐9 gives mixtures of 2,5‐disubstituted tetrahydrofurans 2, 10‐21, favoring formation of the trans isomer. In contrast, an allylic silyl group as in 28‐30 exerts a high degree of stereocontrol, generally affording 2,3‐trans‐disubstituted tetrahydrofurans 31‐36.