Sulfur-containing heterocycles: Facile synthesis of 4H-1,3-thiazines by the reaction of 3-N-acylamino ketones with Lawesson's reagent

The treatment of 3-N-acylamino ketones with Lawesson's reagent [LR: 2,4-bis (p-methoxyphenyl)-1,3,2,4-dithiaphosphetane 2,4-disulfide] afforded the sul fur-containing heterocycles, 4H-1,3-thiazines in moderate to good yields, a long with the corresponding 3-N-thioacylamino ketones.