Process for the preparation of substituted benzofuran derivatives

摘要

PCT No. PCT/EP91/02512 Sec. 371 Date Jun. 25, 1993 Sec. 102(e) Date Jun. 25, 1993 PCT Filed Dec. 27, 1991 PCT Pub. No. WO92/12147 PCT Pub. Date Jul. 23, 1992.Substituted benzofuran derivatives of the formula (I): <IMAGE> I wherein one of R1 and R2 is hydrogen or halogen and the other is, independently, an amino group or a C2-C4 alkanoyl amino group; R3 is hydrogen; a linear or branched C1-C4 alkyl, C1-C4 alkoxy or C2-C4 alkoxycarbonyl group; halogen; or phenyl unsubstituted or substituted by a C1-C4 alkyl group; A is a group -(CH2)n-Het wherein Het is an optionally substituted heteromonocyclic or heterobicyclic ring containing one or two nitrogen atoms, and n is zero or an integer of 1 to 3; and the symbol ..... represents a single or double bond; may be prepared by a process comprising reacting a compound of formula II: <IMAGE> II in which L is a leaving group and R4 is hydrogen or a carboxy protecting group, with a compound of formula III; R'3-C=C-R'3 III to obtain a compound of formula IV; <IMAGE> IV which is then cyclized to obtain a compound of formula V; <IMAGE> V which is reacted with a compound of formula VI; H2N-A VI.