Intermolecular Reductive Heterocyclization of Potassium 2-Acyl-1,1,3,3-tetracyanopropenides

Abstract

2-Acyl-1,1,3,3-tetracyanopropenides undergo intermolecular reductive heterocyclization under the action of mercaptoethanol or sodium borohydride, resulting in the formation of 2-[5-amino-4-cyano-2-alkyl(aryl)furan-3(2H]-ylidene)malononitriles in high yields and excellent purities, These are of interest as potential precursors to organic nonlinear optical (NLO) materials and prospective antibiofilm antimicrobial agents. closure 2-Acyl-1,1,3,3-tetracyanopropenides 1 1 are prospective starting compounds for the synthesis of various heterocycles. The presence of two types of electrophilic centers, a carbonyl group and the cyano groups in the anions of salts 1, give rise to a heterocyclization pathway under the action of nucleophilic reagents resulting in the formation of fivemembered heterocycles. We previously described the transformation of salts 1 into dihydrofuran derivatives (Scheme 1) via reactions with alcohols and oximes (X = OR′), 2 thiols (X = SR′), 3 and hydrogen halides (X = Cl, Br). 4Scheme 1 Synthesis of dihydrofuran derivatives via the reactions of 2-acyl-1,1,3,3-tetracyanopropenides with nucleophilic reagents