An object of the present invention is to provide prasugrel hydrochloride witha reduced content of CATP, and the like.(see multi-step process above)In the formulae, R represents a protecting group for a hydroxyl group.A method for producing prasugrel hydrochloride represented by the aboveformula is provided, characterized by comprising, in step (i), controlling, atlowvalues, the temperature during the addition, optionally dropwise, of achlorinatingagent and the reaction temperature after the addition, optionally dropwise, ofthechlorinating agent.
