Highly Enantioselective α-aminoxylation Reactions Catalyzed by Isosteviol-proline Conjugates in Buffered Aqueous Media
作者:Ya-Jie An、Chuan-Chuan Wang、Yuan-Zhen Xu、Wei-Juan Wang、Jing-Chao Tao
DOI:10.1007/s10562-011-0574-6
日期:2011.8
using nitrosobenzene in phosphate buffer solution, resulting in good to high yields and excellent enantioselectivities without using any additives. At pH 9.1, the amphiphilic catalysts showed a pH responsive ability in phosphate buffer solution, which facilitated the excellent O-selectivity reactions, illustrating a viable approach for the development of asymmetric supra-molecular catalysts.Graphical
通过将 l-脯氨酸与廉价的天然产物异甜菊醇共价连接,设计并合成了手性两亲共轭催化剂。这些催化剂在磷酸盐缓冲溶液中使用亚硝基苯进行醛和酮的不对称 α-氨氧基化反应中表现出显着的效率,在不使用任何添加剂的情况下产生了良好的收率和优异的对映选择性。在 pH 9.1 时,两亲性催化剂在磷酸盐缓冲溶液中表现出 pH 响应能力,促进了优异的 O 选择性反应,说明了开发不对称超分子催化剂的可行方法。
Enantioselectivity Switch
in Direct Asymmetric Aminoxylation Catalyzed by Binaphthyl-Based
Chiral Secondary Amines
Binaphthyl-based amino acids (S)-1 and an aminosulfonamide (S)-2 were applied for directasymmetricaminoxylation with nitrosobenzene. In the presence of either (S)-1 or (S)-2, the aminoxylation of aldehydes proceeded smoothly, and subsequent reduction with NaBH4 gave 2-aminoxyl alcohols with good to excellent enantioselectivities. In each case, binaphthyl-basedchiralamine catalysts (S)-1 and (S)-2