Synthesis of 2H-1,4-benzothiazin-3(4H)-ones and 2H-1,4-benzoselenazin-3(4H)-ones with the aid of samarium(II) iodide

Bis(o-nitrophenyl) disulfides or diselenides were easy to reduce by samarium(II) iodide to produce the active intermediates 2 in situ, which readily react with α-halocarboxylic derivatives to yield the corresponding products 2H-1,4-benzothiazin-3(4H)-ones and 2H-1,4-benzoselenazin-3(4H)-ones, respectively, in moderate to high yields under mild conditions.