Patent ID: 7342116

Claim:
A process for preparing heterocyclic aldehyde, which comprises reacting a heterocyclic compound having at least one hydroxymethyl group bonded to a carbon atom of a heterocyclic ring with a hypohalogenous acid salt in the presence of a base to oxidize said hydroxymethyl group, wherein the reaction is conducted in the co-presence of a 2,2,6,6-tetramethylpiperidine-1-oxyl derivative having at least four 2,2,6,6-tetramethylpiperidine-1-oxyl-4-yl groups, said heterocyclic compound having at least one hydroxymethyl group bonded to a carbon atom of a heterocyclic ring is a pyridinemethanol represented by formula (3): (wherein CH 2 OH and R 2 are substituents bonded to a carbon atom of a pyridine ring; R 2 represents an alkyl group; k is an integer of 0 to 4) and said heterocyclic aldehyde is a pyridinecarbaldehyde represented by formula (4): (wherein R 2 and k are the same as above).