叔胺硫脲催化的2,5-二羟基-1,4-二噻烷与氮叔丁氧羰基醛亚胺的不对称[3+2]环化反应

Asymmetric [3+2]Annulations of 1,4-Di-thiane-2,5-diol and N-Boc Aldimines Catalyzed by Tertiary-amine Thiourea

以双功能手性叔胺硫脲作为催化剂,用于催化2,5-二羟基-1,4-二噻烷与氮叔丁氧羰基(N-Boc)醛亚胺的不对称[3+2]环化反应.实验结果表明,在10%(摩尔分数)手性催化剂的作用下,反应底物均能高产率地转化成目标产物,并且得到高达95%的对映选择性和7∶1的非对映选择性,实现了一系列含有四氢噻唑骨架的双手性中心化合物的合成.

A highly enantioselective asymmetric [3 ＋ 2] annulation of 1,4-di-thiane-2,5-diol and N-tert-butoxy-carbonyl（ N-Boc） aldimines was catalyzed by a bifunctional tertiary-amine thiourea catalyst. The N-Boc aldimine was assumed to be activated and oriented by the hydrogen bonds of the thiourea,meanwhile the tertiary amine of the catalyst would provide suitable basicity to enhance the nucleophilicity of the mercaptoacetaldehyde. This method realized the construction of double chiral center via a one-step synthesis. As a result,a number of chiral thiazolidine scaffolds,which present in bioactive molecules widely,were smoothly synthesized with 10%（ molar fraction） chiral catalysts,and achieved up to 95% enantioselectivity and 7 ∶ 1 diastereoselectivity in good yields.