Nonenzymatic Asymmetric Acylation of meso-Diols

近年来，外消旋仲醇和中二醇的非酶不对称酰化反应受到了广泛的关注。我们还证明了在(S)-脯氨酸衍生的手性二胺存在下，通过与非手性苯甲酰卤化物的反应，外消旋仲醇和中1,2-二醇的不对称酰化。近年来陆续出现了一些以非手性酰化剂催化醇类不对称酰化反应为基础的论文。然而，这两种方法都没有发展到在有机合成中广泛使用的程度。我们建立了一种由(S)-脯氨酸衍生的手性二胺可以作为中介1,2 -二醇催化不对称反应的高效催化剂。在0.5 mol%的手性二胺和化学计量量的三乙胺的存在下，苯甲酰氯成功地催化1,2-二醇的不对称酰化反应，得到了相应的具有良好至优异对映选择性的单苯甲酸酯。用非手性苯甲酰氯在仅0.3 moL%的(S)-脯氨酸衍生的手性二胺和0.5等量的三乙胺的存在下，成功地催化了外消旋仲醇的不对称酰化反应。醇与苯甲酰氯在TMEDA的存在下，在-78℃条件下发生快速酰化反应，得到相应的苯甲酰氯，收率高。

Recently, much attention has been focused on the nonenzymatic asymmetric acylation of racemic secondary alcohols and meso-diols. We have also demonstrated asymmetric acylation of racemic secondary alcohols and meso-1,2-diols by the reaction with achiral benzoyl halide in the presence of a chiral diamine derived from (S)-proline. Some papers which are based on the catalytic asymmetric acylation of alcohols with achiral acylating agents have emerged successively in recent years. However, neither methodology has been developed to such a level as to find widespread use in organic synthesis.We establish that a chiral diamine derived from (S)-proline can function as a highly efficient catalyst for the catalytic asymmetrization of meso-1 , 2-diols. Catalytic asymmetric acylation of mesa-1,2-diols has been successfully performed by the reaction with benzoyl chloride in the presence of 0.5 mol% of chiral diamine combined with a stoichiometric amount of triethylamine to give the corresponding monobenzoate with good to excellent enantioselectivities. Catalytic asymmetric acylation of racemic secondary alcohols has been also successfully performed with achiral benzoyl chloride in the presence of only 0.3 moL% of chiral diamine derived from (S)-proline, combined with 0.5 equivalent of triethylamine.Reactions of alcohols with benzoyl chloride in the presence of TMEDA at -78 ﾟC resulted in very fast acylation to afford the corresponding benzoates in excellent yields.