Expanding the scope of the Newman–Kwart rearrangement — A computational assessment

Abstract

The Newman–Kwart rearrangement (NKR) has been studied for a variety of thioncarbamates using density functional (B3LYP) and ab initio (MP2) methodologies. The results confirm and support the generally accepted mechanism that the NKR proceeds through a four-membered cyclic transition state. The presence of a π system connected via an oxygen linkage to a thiocarbonyl functionality is identified as a crucial structural element for the NKR. The calculations further suggest that the NKR might also be feasible for thioncarbamates derived from π system containing groups other than phenols such as ethenol, ethenediol, and butadienol. The NKR is compared with the Schönberg rearrangements of thioncarbonates.Key words: density functional calculations, localized orbital locator, oxygen–sulfur transposition, thiols.