The first enantioselective direct α-hydroxylation of β-oxo esters was developed by using phase-transfercatalysis. 1-Indanone-derived 1-adamantyl (1-Ad) β-oxo esters, in the presence of commercially available cumyl hydroperoxide and a cinchonine-based ammonium salt, resulted in the corresponding products with 69–91 % yield and 65–74 % ee. The reaction had also been successfully scaled-up to a gram
Kinetic Resolution of Oxaziridines via Chiral Bifunctional Guanidine-Catalyzed Enantioselective α-Hydroxylation of β-Keto Esters
作者:Xiaobin Lin、Sai Ruan、Qian Yao、Chengkai Yin、Lili Lin、Xiaoming Feng、Xiaohua Liu
DOI:10.1021/acs.orglett.6b01614
日期:2016.8.5
efficient kinetic resolution of racemic oxaziridines has been realized via catalytic asymmetric α-hydroxylation of available β-ketoesters. In the presence of a chiral bifunctional guanidine catalyst, a variety of optically active oxaziridines and chiral α-hydroxy β-ketoesters were generated with excellent results (ee’s of up to 99% and 97% and yields of up to 44% and 54%, respectively).
We report high‐performance I+/H2O2 catalysis for the oxidative or decarboxylative oxidative α‐azidation of carbonyl compounds by using sodium azide under biphasic neutral phase‐transfer conditions. To induce higher reactivity especially for the α‐azidation of 1,3‐dicarbonyl compounds, we designed a structurally compact isoindoline‐derived quaternary ammonium iodide catalyst bearing electron‐withdrawing
我们报告了在双相中性相转移条件下使用叠氮化钠对羰基化合物进行氧化或脱羧氧化α-叠氮化的高性能I + / H 2 O 2催化。为了诱导更高的反应活性,尤其是对于1,3-二羰基化合物的α-叠氮化,我们设计了结构紧凑的异吲哚啉衍生的带有吸电子基团的季碘化铵催化剂。I + / H 2 O 2的非生产性分解途径催化量可以通过使用催化量的自由基捕获剂来抑制。这种氧化偶合耐受各种官能团,可以很容易地应用于结构多样的复杂分子的后期α-叠氮化。此外,我们实现了1,3-二羰基化合物的对映选择性α-叠氮化,这是手性次碘酸盐催化剂与对映选择性分子间氧化偶联的第一个成功实例。
Enantioselective α-Hydroxylation of β-Keto Esters Catalyzed by Cinchona Alkaloid Derivatives
A highly efficient α-hydroxylation of β-ketoesters catalyzed by cupreidine in the presence of cumyl hydroperoxide (CHP) was achieved. The reaction was applied to a wide variety of β-ketoesters to give products in high yields (up to 95%) with excellent enantioselectivities (up to 97% ee). The reaction had been successfully scaled up to a gram quantity and (S)-5-chloro-2-hydroxy-1-oxo-2,3-dihydro-
asymmetric α‐hydroxylation of β‐indanone esters and β‐indanone amides using peroxide as the oxidant was realized with a new C‐2′ substituted Cinchona alkaloid derivatives. The two enantiomers of α‐hydroxy‐β‐indanone esters could be obtained by simply changing the oxidant. This protocol allows a convenient access to the corresponding α‐hydroxy‐β‐indanone esters and α‐hydroxy‐β‐indanone amides with up to