Thionation ofω-Acylamino Ketones withLawesson's Reagent: Convenient Synthesis of 1,3-Thiazoles and 4H-1,3-Thiazines
摘要:
The reaction of omega -acylamino ketones with Lawesson's reagent (=2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide; LR) is described. Treatment of 2-acylamino ketones 1 (n = 0) with LR gave 1,3-thiazole derivatives 3 in good yields (Scheme I and Table 1). The 4H-1,3-thiazines 4 were obtained as main products by treatment of 3-acylamino ketones 2 (n = 1) with an equimolar amount of LR, while mainly the corresponding 3-(thioacyl)amino ketones 5 were isolated when 0.5 equiv. of LR was used. The 3-acylamino esters 7 also reacted with LR to give the corresponding 3-(thioacyl)amino esters 8 (Scheme 3 and Table 2).