Radical Route to 1,4-Benzothiazine Derivatives from 2-Aminobenzenethiols and Ketones under Transition-Metal-Free Conditions.

Transition-metal-free radical access to 1,4-benzothiazine derivatives from o-aminobenzenethiols is disclosed. This procedure is available for various ketones including α,β-unsaturated, cyclic, linear, and fluoroalkyl ketones to generate a number of 1,4-benzothiazines, which exist in numerous bioactive and natural molecules, rendering this protocol attractive to both synthetic and medicinal chemistry.