STEREOCONTROLLED SYNTHESIS OF HIGHLY FUNCTIONALIZED 2,4-DIOXAHYDRINDANS VIA DEBENZYLATING TETRAHYDROFURAN RING FORMATION

4C-(1-Hydroxyalkyl)-substituted 2,3,6-tri-O-benzyl-glucopyranosides (S )-2a, (R)-2a, and 6 are transformed at low temperature into the corres ponding triflates; they undergo immediately. an S(N)2-type reaction le ading to the formation of a trans-fused tetrahydrofuran ring under los s of the 6-O-benzyl group, thus yielding 2,4-dioxahydrindans (R)-3a, ( S)-3a, and 7, respectively. 4C(alpha-Hydroxyallyl) and 4C(alpha-hydrox ybenzyl) derivatives of 2 lead to 6-O-debenzylation and triflate/hydri de exchange reactions, thus yielding entirely different reaction produ cts.