A new and highly efficient synthesis of (＋)-biotin which is based on the ready availability of L-cysteine or L-cystine as a chiral starting material has been achieved, which contains 10 steps reactions with over 30% yield. From L-cysteine involving amidoalkylation of hydroxy imidazothiazolone 2 to furnish C-7-substituted imidazo-thiazolones 3, then rearrange and hydrolyze to form 4 by Collins oxidation, reducetion of intermediate 4 and so on, the requisite biotin skeletal structure is established.

Key words: amidoalkylation, L-cysteine, d-biotin