A Novel, Industrially‐feasible Synthetic Route to (+)‐Biotin from L‐Cysteine

A novel, industrially viable synthetic route to (+)‐biotin has been developed starting from L ‐cysteine via the known key thiolactone intermediate. The route takes advantage of the in‐built stereochemistry of the cysteine starting material and the best features of the two current industrialized processes. The key transformations are the conversion of L ‐cysteine into a hydantoin avoiding racemization followed by catalytic cyanation and thiolactonization to form the required thiolactone intermediate. This known intermediate can be readily further transformed into (+)‐biotin.