Mechanistic Studies on Alicyclic and Heterocyclic Compounds Using Newer Synthetic Methodologies

Abstract

An efficient method for the transformation of N-substituted-N$'$-benzoylthioureas to substituted N-benzoxazol-2-yl-amides using diacetoxyiodobenzene (DIB) will be described in this presentation. The transformation follows C-O bond formation leading to the benzoxazole derivative due to oxidative dehydrogenation by DIB, instead of the expected C-S bond formation of the benzothiazole moiety. The C-O bond formation leading to benzoxazole is due to consecutive acylation and deacylation in conjunction with the reduction of two moles of DIB. A plausible mechanism was proposed for the reaction, and density functional calculations were also performed to study the reaction mechanism. Unexpectedly, the reaction follows a different pathway leading to C-O bond formation between the carbonyl oxygen and the ortho-carbon of the aryl moiety, resulting in oxazole ring formation, which will be presented here. A new approach for the conversion of aryl amines having no $\alpha$-methylene group to aryl nitriles using dimethyl carbonimidodithioates by intramolecular stabilization, particularly 1,2-carbon migration to give the products, will also be highlighted. Here, the conversion of a C-N bond to a C-C bond takes place.