Patent ID: 6900298

Claim:
A process for producing a nucleic acid derivative, which comprises condensing a dinitrogen 6-membered heterocyclic compound or a trinitrogen 5-membered heterocyclic compound with a pentose in the presence of an iron halide; wherein the dinitrogen 6-membered heterocyclic compound is a compound represented by the following formula (A) or (A′): wherein R 1 represents a halogen atom, a cyano group, a carboxylic ester group, carbamoyl group, a formyl group, an acyl group, an amino group or an alkyl group; G 1 , G 2 , G 3 , G 4 , G 5 and G 6 each independently represent an alkyl group; and n is an integer of 0 to 2, provided that in case where n is 2, a plural number of R 1 s may be different from each other, and two R 1 s adjacent to each other may form together a carbon ring or a heterocycle; and the trinitrogen 5-membered heterocyclic compound is a compound represented by the following formula (B) or (B′); wherein R 1 , G 1 , G 2 , G 3 and n are each as defined above; and wherein the pentose is a compound represented by the following formula (C): wherein R 2 to R 2′″ each independently represent an acyl group.