Process for producing benzofuran derivative

A process for producing a compound represented by the formula:

• wherein ring A is a benzene ring that may be optionally further substituted in addition to the group represented by W, and other symbols are as defined below, or a salt thereof;
• which comprises reacting a compound represented by the formula:
• wherein R1 and R2 are the same or different and each is a hydrogen atom, an optionally substituted hydrocarbon group or an optionally substituted heterocyclic group, or R1 and R2 may be taken together with the adjacent carbon atom to form an optionally substituted 3- to 8-membered homocyclic or heterocyclic ring, Y is a halogen atom, ring A is a benzene ring that may be optionally further substituted in addition to the group represented by Y, and ring B is an optionally substituted benzene ring, or a salt thereof, with a compound represented by the formula:
• WH
• wherein W is:
• (i) a group represented by the formula:
• wherein ring C is an optionally substituted benzene ring, and ring D is a 5- to 7-membered nitrogen-containing heterocyclic ring that may be optionally substituted with halogen or an optionally substituted hydrocarbon group, or
• (ii) a group represented by the formula:
• wherein R3 is (1) a hydrogen atom, (2) an aliphatic hydrocarbon group that is substituted with an optionally substituted aromatic group and may be optionally further substituted, or (3) an acyl group containing an optionally substituted aromatic group;
• R4 is a hydrogen atom, an optionally substituted hydrocarbon group or an acyl group;
• or R3 and R4 may be taken together with the adjacent nitrogen atom to form an optionally substituted 4- to 8-membered nitrogen-containing ring, or a salt thereof and thereafter, if necessary, deprotecting the resultant product.