Intermediate for biotin and process for producing the same

摘要

The present invention is to provide a process for preparing a synthetic intermediate of biotin which is industrially advantageous, and discloses a process for preparing a compound represented by the formula (I): wherein R¹ and R² may be the same or different from each other, and each represents hydrogen atom, a benzyl group which may have a substituent(s) on the benzene ring, a benzhydryl group which may have a substituent(s) on the benzen ring, or a trityl group which may have a substituent(s) on the benzene ring, R³ represents cyano group, carboxyl group, an alkoxycarbonyl group, an alkylthiocarbonyl group, or a carbamoyl group which may have a substituent, or a salt thereof which comprises subjecting a compound represented by the formula (II-a): wherein the symbols have the same meanings as defined above, or a salt thereof to ring transformation.