Synthesis and characterization of some heterocyclic derivatives by cyclization of carbohydrate thiosemicarbazones. Part I

We report the synthesis of 2,3-dihydro-1,3,4-thiadiazoles and 1,3,4-thiadiazoles from 1,2:3,4-di-O-iso-propylidene-α-D-galacto-1,6-hexodialdo-1,5-pyranose thiosemicarbazone. The physical and spectro-scopic characterizations of the heterocyclic derivatives as well as the intermediate product are described. We present the prefered conformation in solution using computational calculations and spectroscopic data. The possibilities of chiral induction of the cyclization reaction are discussed.