Synthesis of 1,4,2‐Oxathiazoles via Norrish Type II Generation of Thiocarbonyls

Abstract

AbstractSeveral previously inaccessible 1,4,2‐oxathiazoles have been prepared by [3 + 2] cycloaddition of nitrile oxides and highly reactive thioaldehydes and thioketones. Generated via photolytic cleavage of 2‐phenacyl sulfides (Norrish type II photolytic cleavage), these reactive thiocarbonyls provide a broad library of 1,4,2‐oxathiazole structures which other methods have failed to achieve. We also report the thermal fragmentation of these 1,4,2‐oxathiazoles, in which both fragmentation to nitrile or isothiocyanate may occur. 5H‐1,4,2‐Oxathiazoles have shown to fragment to nitrile even in the absence of base. At elevated temperatures, fragmentation to isothiocyanates occurred in preference to nitriles.