Catalytic tin radical mediated tricyclisations. Part 2 †‡

Propenyl 4-O-propargyl-, propargyl 4-O-propenyl-, and propargyl 4-O-propargyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranosides undergo catalytic, tin radical initiated, cascade reactions, in which three rings are constructed in a single reaction. In each case, a lack of stereoselectivity in the second cyclisation results in an additional product which is produced non-catalytically. The dienes which result from catalytic cyclisation of propargyl 4-O-propargyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranosides, undergo in situ hydrostannylation to give unusual allylstannanes.