Reactions of tetrasulfur tetranitride antimony pentachloride complex (S4N4 SbCl5) with primary beta-enaminones and beta-enamino esters: Synthesis of 4-substituted 3-aroyl- and 3-ethoxycarbonyl-1,2,5-thiadiazoles

Abstract

The reaction of tetrasulfur tetranitride antimony pentachloride complex (S4N4SbCl5) with 3-amino-3-alkyl-1-aryl-2-propenones and 3-amino-1,3-diaryl-2-propenones in toluene at 100 degrees C produced 4-substitued 3-aroyl-1,2,5-thiadiazoles (3a-p) in 12 to 57% yields. Similarly treatment of beta-enamino esters with S4N4SbCl5 complex under the same conditions as for the reaction with beta-enaminones gave ethyl 3-aryl-1,2,5-thiadizole-4-carboxylates (3q-x) in 41 to 54% yields. The formation of the products may be explained by the same mechanism as that proposed for the formation of 1,2,5-thiadizoles from 5-substitued 3-alkyl- and 3-aryl-isoxazoles and S4N4SbCl5 complex.