Patent ID: 7655817

Claim:
A production method of a compound represented by the formula (IV): wherein R 8 is a hydrogen atom, a lower alkyl group optionally having substituent(s), an aralkyl group optionally having substituent(s), an aryl group optionally having substituent(s) or a heteroaryl group optionally having substituent(s); R 9 and R 10 are each independently an electron withdrawing group, or R 8 and R 9 optionally form, together with the adjacent carbon atom, a ring containing an electron withdrawing group and optionally having substituent(s) (said ring is optionally condensed with an aromatic hydrocarbon), provided that R 9 and R 10 are not the same group; C*** is an asymmetric carbon; and PG is a protecting group, or a salt thereof, which comprises reacting a compound represented by the formula (II): wherein PG is as defined above, with a compound represented by the formula (III): wherein R 8 , R 9 and R 10 are as defined above, in the presence of a compound represented by the formula (I): wherein X is S or O; C* and C** are each independently an asymmetric carbon; R 1 and R 2 are the same or different and each is a lower alkyl group optionally having substituent(s), an aralkyl group optionally having substituent(s) or an aryl group optionally having substituent(s), or R 1 and R 2 optionally form, together with the nitrogen atom they are bonded to, an aliphatic heterocycle optionally having substituent(s) (the aliphatic heterocycle is optionally condensed with an aromatic hydrocarbon); R 3 is a lower alkyl group optionally having substituent(s), an aralkyl group optionally having substituent(s), an aryl group optionally having substituent(s) or a heteroaryl group optionally having substituent(s); R 4 and R 5 are the same or different and each is a lower alkyl group optionally having substituent(s), an aralkyl group optionally having substituent(s) or an aryl group optionally having substituent(s), or R 4 and R 5 optionally form, together with the asymmetric carbons they are respectively bonded to, a homocyclic ring optionally having substituent(s) or a heterocycle optionally having substituent(s) (the homocyclic ring and the heterocycle are each optionally condensed with an aromatic hydrocarbon); and R 6 and R 7 are the same or different and each is a hydrogen atom or a lower alkyl group optionally having substituent(s), or a salt thereof.