Method for producing solifenacin or salts thereof

A method for producing solifenacin or a pharmaceutically acceptable salt thereof, which is a production method selected from a production method group G, wherein the production method group G is a group consisting of the following production methods (1) to (4),

• (1) a method for producing solifenacin or a pharmaceutically acceptable salt thereof, which comprises allowing a compound represented by a formula (I)
• [in the formula, Lv represents 1H-imidazol-1-yl, 2,5-dioxopyrrolidin-1-yloxy, 3-methyl-1H-imidazol-3-ium-1-yl or chloro]
• and (R)-quinuclidin-3-ol to undergo condensation,
• (2) a method for producing solifenacin succinate, which comprises allowing succinic acid to react with a compound represented by a formula (II)
• [in the formula, stereochemistry of the 1-position of phenyl-substituted tetrahydroisoquinoline is a mixture of (R)-form and (S)-form],
• (3) a method for producing solifenacin or a pharmaceutically acceptable salt thereof, which comprises allowing a compound represented by a formula (III)
• [in the formula, R1 represents a lower alkyl which may be substituted]
• and (S)-1-phenyl-1,2,3,4-tetrahydroisoquinoline or a salt thereof to undergo condensation, and
• (4) a method for producing solifenacin or a pharmaceutically acceptable salt thereof, which comprises allowing a compound represented by a formula (IV)
• [in the formula, R2 represents a secondary lower alkyl or a tertiary lower alkyl, which may be respectively substituted]
• and (R)-quinuclidin-3-ol to undergo reaction in the presence of an alkali metal lower alkoxide.