The reactions of n-butylamine (BuNH 2 ), 2-aminoethanol (H 2 N(CH 2 ) 2 OH), diethylamine (Et 2 NH), and phenylhydrazine (PhN 2 H 3 ) 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 1 H-and 13 C-NMR in aprotic solvent solution. The course of the reactions depended on the substrate-nucleophile combination: Et 2 NH added to 1a or 1b, forming the corresponding thiadiazolines in an equilibrium monoaddition reaction. The equilibrium constants were evaluated and compared. With primary amines and PhN 2 H 3 , the nucleophile added to both C --N double bonds of 1a and displaced the sulfamide moiety. In the case of the reaction of 1a with PhN 2 H 3 , the intermediate monoaddition thiadiazoline, 3-(2phenylhydrazino)-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide, was also isolated. BuNH 2 and H 2 N(CH 2 ) 2 OH reacted with 1a to give a-bis-imines, while 1a with PhN 2 H 3 gave the a-bis-hydrazone. The configurations of benzil bis(ethanolimine) and benzilosazone were determined by single crystal x-ray diffraction analysis as Z,Z. BuNH 2 and PhN 2 H 3 reduced 1b to the corresponding thiadiazoline compound 1bH 2 .
EXPERIMENTALCompounds 1a, b were synthesized according to Wright. 7 Standard methods 8-10 were used for purification of commercial solvents and nucleophiles. The solvents were JOURNAL OF PHYSICAL ORGANIC CHEMISTRY