One-pot Synthesis of Highly Functionalized Pyrido-1,3-thiazin-4-ones Using Unprotected Sugars in a Task-specific Ionic Liquid, [Bmim]SCN

Abstract

An original four-component coupling strategy to iminosugar-annulated 1,3-thiazines, that is, pyrido-1,3-thiazin-4-ones using unprotected D-xylose/D-glucose, 2-phenyl-1,3-oxazolan-5-one, [bmim]SCN, and NH4OAC/RNH2 is reported. The strategy involves a task-specific ionic liquid, [bmim]SCN-promoted cascade reactions involving hydrothiocyanation and aminoacetylative azaheterocyclization. The reactions give excellent yields (82-95%) and are highly diastereoselective (>94%) in favor of cis isomer.