Stereospecific C-N Bond Cleavage of 4-Silylated 1,2-Thiazetidine 1,1-Dioxides with EtAlCl2 or AlCl3: Formation of (E)-Vinylsulfonamides.
作者:Tetsuo IWAMA、Atsuko TAKAGI、Tadashi KATAOKA
DOI:10.1248/cpb.46.757
日期:——
Monosilylation of 1, 2-thiazetidine 1, 1-dioxides (β-sultams) 3 gave (3R*, 4S*)-4-monosilyl-β-sultams 4 stereoselectively. Disilylated β-sultams 5 were obtained by the use of trimethylsilyl chloride. Treatment of 4-monosilyl-β-sultams 4 with EtAlCl2 caused stereospecific C-N bond cleavage owing to β-cation stabilization of the silicon group to provide (E)-vinylsulfonamides (E)-7. (E)-α-Silylstyrylsulfonamides (E)-7j-l were generated in the reaction of 4, 4-disilyl-β-sultams 5 with EtAlCl2. Reaction of 4-silyl-β-sultams with AlCl3 afforded N-dealkylated (E)-vinylsulfonamides in good yields. Reaction of (E)-α-silylstyrylsulfonamide (E)-10 with benzaldehyde in the presence of tetrabutylammonium fluoride and BF3·Et2O provided the allylic alcohol (E)-12.
将 1,2-噻嗪啶 1,1-二氧化物(β-舒坦类)3 单硅烷化后,可立体选择性地得到 (3R*,4S*)-4-单硅烷-β-舒坦类 4。使用三甲基氯硅烷可以得到二硅烷基化的 β-苏丹酰胺 5。用 EtAlCl2 处理 4-单硅烷基-β-苏丹酰胺 4 时,由于硅基的β阳离子稳定作用,C-N 键发生了立体特异性裂解,从而得到了(E)-乙烯基磺酰胺 (E)-7。(E)-α-硅烷磺酰胺 (E)-7j-l 是在 4,4-二硅烷-β-舒坦 5 与 EtAlCl2 的反应中生成的。4, 4-二硅烷基-β-舒坦与 AlCl3 反应生成 N-脱烷基的 (E)-乙烯基磺酰胺,产率良好。在四丁基氟化铵和 BF3-Et2O 存在下,(E)-α-硅烷基苯乙烯磺酰胺 (E)-10 与苯甲醛反应,得到烯丙基醇 (E)-12。