An Approach to Total Synthesis of (+)-Lycoricidine

A convergent synthesis of a protected version of (+)-lycoricidine has been accomplished in 13 steps from l-arabinose. Preparation of the aminocyclitol moiety 50 employed a novel vinylsilane-terminated N-sulfonyliminium ion cyclization of vinylsilane aldehyde 42. Closure of the B-ring using an intramolecular Heck reaction afforded lycoricidine derivative 58. An unexpected cyclization of vinylsilane aldehyde 42 allowed for the stereodivergent preparation of semiprotected conduritols 43 and 45.