Metal mediated synthesis of 2, 3-dihydro benzofuran derivatives

Abstract

Dihydrobenzofuran (DHB) is the key structure moiety of many highly bilogically active materials, constructing pharmaceuticals (furadm), lignans and other biologically natural compounds (pterocarpans). Pterocarpans have a 2,3-Dihydrobenzofuran skeleton which could be response to fungi infections and biological activities against such as HIV, central nervous system(CNS) injury and malaria. An efficient one pot synthesis of 2,3-dihydrobenzofurans (14a-18a) derivatives by bis-triphenyl phosphine palladium(II) chloride, bis-triphenyl phosphine cobalt(II) chloride, bis-triphenyl phosphine nickel(II) bromide and Pd/Cu bimetallic nano particles catalyzed reactions of 2-iodophenol derivatives with terminal alkenes is reported. The reactions of 2-iodophenol derivatives (5-8) with acrylic esters (13,13a) were performed in presence of different catalyst [Pd(Ph3P)2Cl2, Co(Ph3P)2Cl2, Ni(Ph3P)2Br2, Pd/Cu Bimetallic nano particles], triethylamine (Et3N) and DMF under nitrogen atmosphere for 20-24 hrs at 80-120 oC to obtain alkyl 2, 3-dihydrobenzofuran-2-ylcarboxylates (14a-18a) in good yield %(50-70) as shown in the scheme

Condition i Pd(Ph3P)2Cl2, DMF, Et3N, N2, 80-100 oC, 20-24 hrs ii Co(Ph3P)2Cl2, DMF, Et3N, N2, 80-100 oC, 20-24 hrs iii Ni(Ph3P)2Br2, DMF, Et3N, N2, 80-100 oC, 20-24 hrs iv Pd/Cu Bimetallic nano particles, DMF, Et3N, N2, 80-100 oC, 20-24 hrs