[1]Benzofuro[3,2-c]pyridine synthesis and coordination reactions

( E )-3-(1-Benzofuran-2-yl)propenoic acid ( 1 ) was prepared from 1-benzofuran-2-carbaldehyde under the Doebner’s conditions. The obtained acid was converted to the corresponding azide 2 , which was cyclized by heating in diphenyl ether to [1]benzofuro[3,2- c ]pyridine-1(2 H )-one ( 3 ). This compound was aromatized with phosphorus oxychloride to chloroderivative 4 which was reduced with zinc and acetic acid to the title compound 5 . [1]Benzofuro[3,2- c ]pyridine-2-oxide ( 6 ) was synthesized by reaction of 5 with 3-chloroperoxybenzoic acid in dichloromethane. Treatment of 6 with benzoyl chloride and potassium cyanide (Reissert-Henze reaction) was shown to produce the corresponding [1]benzofuro[3,2- c ]pyridine-1-carbonitrile ( 7 ). The title compound was used for preparation of complexes Cu 2 (ac) 4 (bfp) 2 ( 8 ) and CoCl 2 (bfp) 2 ( 9 ), where ac=CH 3 CO 2 − and bfp=[1]benzofuro[3,2-c]pyridine. Both oxygen atom of carboxylate ions is used in the coordination to Cu(II). Thermal properties of the complexes 8 and 9 have been studied by TG and DTA and both complexes exhibited high thermal stability while complex 9 are thermally more stable than complex 8 .