Reactions of the activated, rigid, α-diazomethine group of 1,2,5-thiadiazole 1,1-dioxides with nitrogenated nucleophiles.: Part III:: aliphatic monoamines and phenylhydrazine

The reactions of n-butylamine (BuNH2), 2-aminoethanol (H2N(CH2)(2)OH), diethylamine (Et2NH), and phenylhydrazine (PhN2H3) with 3,4-diphenyl-(1a) and phenanthro[9,10-c]-1,2,5-thiadiazole 1,1-dioxide (1b) were studied by cyclic voltammetry (CV) and H-1- and C-13-NMR in aprotic solvent solution. The course of the reactions depended on the substrate-nucleophile combination: Et2NH added to la or 1b, forming the corresponding thiadiazolines in an equilibrium monoaddition reaction. The equilibrium constants were evaluated and compared. With primary amines and PhN2H3, the nucleophile added to both C=N double bonds of la and displaced the sulfamide moiety. In the case of the reaction of la with PhN2H3, the intermediate monoaddition thiadiazoline, 3-(2-phenylhydrazino)-3,4-diphenyl- 1,2,5-thiadiazoline 1,1-dioxide, was also isolated. BuNH2 and H2N(CH2)(2)OH reacted with la to give alpha-bis-imines, while la with PhN2H3 gave the alpha-bis-hydrazone. The configurations of benzil bis(ethanolimine) and benzilosazone were determined by single crystal x-ray diffraction analysis as Z,Z. BuNH2 and PhN2H3 reduced 1b to the corresponding thiadiazoline compound 1bH(2). Copyright (c) 2006 John Wiley & Sons, Ltd.