Organocatalytic conjugate addition of α-nitroacetates to β,γ-unsaturated α-keto esters and subsequent decarboxylation: synthesis of optically active δ-nitro-α-keto esters
作者:Rui-jiong Lu、Wen-tao Wei、Jin-jia Wang、Shao-zhen Nie、Xue-jing Zhang、Ming Yan
DOI:10.1016/j.tet.2012.09.014
日期:2012.11
Organocatalytic asymmetric conjugate addition of tert-butyl nitroacetates to β,γ-unsaturated α-keto esters has been developed. The subsequent in situ hydrolysis–decarboxylation of the adducts provided 5-nitro-2-oxopentanoates. A pyrrolidine-based thiourea-tertiary amine was identified as the best catalyst. A number of γ-aryl, γ-alkyl, and γ-heteroaryl β,γ-unsaturated α-keto esters and α-substituted
已经开发了硝基乙酸叔丁酯向β,γ-不饱和α-酮酯的有机催化不对称共轭加成。加合物的随后原位水解-脱羧提供了5-硝基-2-氧戊酸。吡咯烷基硫脲叔胺被认为是最好的催化剂。在转化中检查了许多γ-芳基,γ-烷基和γ-杂芳基β,γ-不饱和α-酮酯和α-取代的叔丁基硝基乙酸酯。通常,以良好的产率(高达97%)和对映选择性(高达94%ee)获得5-硝基-2-氧戊酸。产物易于通过催化氢化转化为手性脯氨酸衍生物。