Method for producing sulfonyl chloride compound

A production method of a compound represented by the formula (VI):

• wherein
• R1 is a pyridin-3-yl group optionally substituted by 1 to 3 substituents selected from (i) halogen, (ii) cyano, (iii) C1-6 alkyl optionally substituted by 1-5 halogens, (iv) C1-6 alkoxy optionally substituted by 1-5 halogens, (v) an amino group optionally substituted by C1-6 alkyl and (vi) C1-6 alkoxy-carbonyl,
• R2 is
• (a) a C6-14 aryl group optionally substituted by 1-5 substituents selected from (i) a halogen atom, (ii) cyano, (iii) C1-6 alkyl optionally substituted by 1-5 halogens, (iv) C1-6 alkoxy optionally substituted by 1-5 halogens, (v) acetyl, (vi) C3-7 cycloalkyl, (vii) C1-6 alkylsulfonyl, (viii) C1-6 alkylthio optionally substituted by 1-5 halogens and (ix) C1-6 alkylsulfinyl,
• (b) a thienyl group optionally substituted by 1 to 3 substituents selected from (i) a halogen atom, (ii) cyano, (iii) C1-6 alkyl optionally substituted by 1-5 halogens, (iv) C1-6 alkoxy optionally substituted by 1-5 halogens and (v) acetyl, or
• (c) a pyridyl group optionally substituted by 1 to 4 substituents selected from (i) a halogen atom, (ii) cyano, (iii) C1-6 alkyl optionally substituted by 1-5 halogens, (iv) C1-6 alkoxy optionally substituted 1-5 halogens, (v) acetyl and (vi) nitro,
• R3 and R4 are each independently a hydrogen atom, a C1-6 alkyl group, a C1-6 alkyl-carbonyl group, a fluorine atom or a chlorine atom,
• and R5 is an alkyl group or a salt thereof,
• comprising reacting, without isolation, the pyridine-3-sulfonyl chloride compound represented by the following formula (II):
• R1—SO2Cl (II)
• wherein R1 is as defined above, which is obtained by reacting a pyridine-3-sulfonic acid compound with phosphorus pentachloride in a solvent of chlorobenzene or trifluoromethylbenzene,
• with a compound represented by the formula (III):
• wherein each symbol is as defined above, or a salt thereof to produce a compound represented by the formula (IV):
• wherein each symbol is as defined above,
• or a salt thereof, and reacting the compound with a compound represented by the formula (V):
• R5—NH2 (V)
• wherein R5 is as defined above, or a salt thereof in the presence of a reducing agent.