Synthesis of some benzofuran and furocoumarin derivatives for possible biological activity

Condensation of 5-formyl-6-methoxy-2,3-diphenylbenzofuran (I) and 6-formyl-5-methoxy-2,3-diphenylbenzofuran (II) with aliphatic or aromatic primary amines led to the formation of the corresponding anils (IIIa-k and IVa-c). The anils (IIIa,f,k or IVa-c) reacted with ethyl cyanoacetate, ethyl acetoacetate, or diethyl malonate to form the respective esters (Va-c or VIa-c). When Va-c or VIa-c were treated with pyridine hydrochloride, demethylation occurred followed by cyclization to form the corresponding furocoumarins (VIIa-c or VIIIa-c). Reduction of the anils using sodium borohydride furnished the corresponding Mannich bases (Xa-d and XI). The antimicrobial activity of compounds IIIi, IVc, Va, VIa, and VIIIa was investigated.