Diastereospecific epoxidation and highly regioselective ring-opening of (+)-valienamine: practical synthesis of (+)-valiolamine

An efficient and practical synthesis of (+)-valiolamine starting from readily available aminocyclitol (+)-valienamine in five steps and up to 80% total yield in gram-scale quantities is reported. Diastereospecific epoxidation by means of substrate directable reaction and regioselective ring-opening of corresponding epoxide are the key reactions in the synthesis, which circumvent laborious purification of products using chromatographical separation. The detailed mechanisms of epoxidation and ring-opening attacked by halide, including the directing and steric hindrance effect, are also discussed.