The present invention provides a compound useful as a synthetic intermediate for an anti-HIV agent having an integrase inhibitory activity, and a production method thereof, and a production method of an anti-HIV agent using the synthetic intermediate. Specifically, for example, a compound represented by the formula (2′): wherein R is a fluorine atom or a methoxy group, and R400 is a hydrogen atom or a C1-C4 alkyl group, or a salt thereof, and a production method thereof, and a production method of an anti-HIV agent using the synthetic intermediate.