The reactions of O-allyl S-alkyl dithiocarbonates of codeine and isocodeine were examined under thermal and catalytic conditions. Heating of a xylene solution of xanthates (3, 4, and 5) gave the corresponding S-allyl S-alkyl dithiocarbonates (6, 7, and 8) via [3, 3] sigmatropic rearrangement in high yields, overcoming the difficulty of attack on the hindered α-face. On the other hand, in the case of isocodeine, the formation of xanthates followed by the rearrangement took place without heating to afford the dithiocarbonates (9, 10, and 11). Furthermore, compound 10 rearranged with extrusion of COS to give the sulfide (14). The reactions of 3, 6, and 9 with phosphine-palladium (0) complex and a Lewis acid as catalysts were also examined. When 3 or 6 was treated with (Ph3P)4Pd, elimination reaction proceeded to give 6-demethoxythebaine (17). The reactions of 6 and 9 with TiCl4 yielded the corresponding cyclic dithiocarbonates 18 and 19.
在热力学和催化条件下,考察了
可待因和异
可待因的O-烯丙基S-烷基二
硫代
碳酸盐的反应。将黄原酸盐(3、4和5)的二
甲苯溶液加热,通过[3, 3]同位素重排反应高效地获得了相应的S-烯丙基S-烷基二
硫代
碳酸盐(6、7和8),克服了α-位阻面的进攻难题。另一方面,在异
可待因的情况下,形成黄原酸盐后无需加热即可发生重排,生成二
硫代
碳酸盐(9、10和11)。此外,化合物10通过排出COS,重排生成了
硫醚(14)。还考察了3、6和9与
磷钯(0)配合物及Lewis酸作为催化剂的反应。当3或6与(Ph3P)4Pd反应时,发生了消除反应,生成6-去甲氧基
蒂巴因(17)。6和9与TiCl4反应生成了相应的环状二
硫代
碳酸盐18和19。