Patent ID: 7994367

Claim:
A method for producing a benzaldehyde compound represented by the formula (4): wherein Q 1 and Q 2 each independently represent a hydrogen atom; an alkyl group which may be substituted with at least one group selected from the group consisting of an alkoxy group, an alkylthio group, a phenylthio group, an alkanesulfonyl group which may be substituted with a fluorine atom, a benzenesulfonyl group which may be substituted with a nitro group or an alkyl group, and a dialkylamino group which may be substituted with a phenyl group; an alkoxy group which may be substituted with at least one fluorine atom; an acyloxy group; an alkanesulfonyloxy group which may be substituted with at least one fluorine atom; a benzenesulfonyloxy group which may be substituted with at least one group selected from the group consisting of a nitro group and an alkyl group; a trialkylsilyloxy group; or an aryloxy group which may be substituted with at least one selected from the group consisting of an alkoxy group and a fluorine atom, n represents 1 or 2, and Ar represents a phenyl group which may be substituted with at least one selected from the group consisting of an alkyl group and a fluorine atom, comprising reacting a compound represented by the formula (3): wherein X 1 represents a chlorine atom, a bromine atom or an iodine atom, and Q 1 , Q 2 , n and Ar are respectively the same meaning as above, with magnesium metal to obtain a Grignard compound and then reacting the obtained Grignard compound with a formylating agent.