Copper-Catalyzed Cascade Syntheses of 2H-benzo[b][1,4]thiazin-3(4H)-ones and Quinoxalin-2(1H)-ones through Capturing S and N Atom Respectively from AcSH and TsNH2

A copper-catalyzed cascade method has been developed to synthesize the 2H-benzo[b][1,4]thiazin-3(4H)-ones from 2-halo-N-(2-halophenyl)-acetamides 1 and AcSH via the S(N)2/deacetylation/coupling process, and to synthesize the quinoxalin-2(1H)-ones from 1 and TsNH2 via the S(N)2/coupling/desulfonation process. The target products were obtained with diversity at three positions on their scaffolds.