| abstract |
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): n n n n n n n n n n n n wherein R 1 and R 2 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, R 3 represents cyano group, carboxyl group, an alkoxycarbonyl group, an alkylthiocarbonyl group, or a carbamoyl group which may have a substituent,n nor a salt thereof which comprises subjecting a compound represented by the formula (II-a):n n n n n n n n n n n n n n n n n wherein the symbols have the same meanings as defined above,n nor a salt thereof to ring transformation. |