An allylicC–H acyloxylation of terminalalkenes with 4-nitrobenzoic acid was assisted by a bidentate-sulfoxide-ligated palladium catalyst combined with 1,4-benzoquinone and Ag2CO3 under mild reaction conditions. The catalytic activity was remarkably enhanced by Ag2CO3 as an additive and 4-nitrobenzoic acid as a carboxylate source; both components were essential to exhibiting high catalytic activity
在温和的反应条件下,末端烯烃与 4-硝基苯甲酸的烯丙基 C-H 酰氧基化反应由双齿亚砜连接的钯催化剂与 1,4-苯醌和 Ag 2 CO 3组合辅助。Ag 2 CO 3作为添加剂和4-硝基苯甲酸作为羧酸盐源显着提高了催化活性;这两种组分对于表现出高催化活性、高支链选择性和钯催化剂负载量低的宽底物范围都是必不可少的。7-辛烯酸乙酯 ( 1a ) 的支链选择性烯丙基酰氧基化得到产物 6,8-二羟基辛酸乙酯 ( 5 ),这是一种有用的合成中间体 ( R)-α-硫辛酸。
Catalytic Asymmetric Synthesis of Chiral Allylic Esters
作者:Stefan F. Kirsch、Larry E. Overman
DOI:10.1021/ja0425583
日期:2005.3.9
Trichloroacetimidate derivatives of prochiral (Z)-2-alken-1-ols react at room temperature with carboxylic acids to give chiral 3-acyloxy-1-alkenes in high enantiopurity in the presence of di-mu-acetatobis[(eta5-(S)-(pR)-2-(2'-(4'-methylethyl)oxazolinyl)cyclopentadienyl,1-C,3'-N)(eta4-tetraphenylcyclobutadiene)cobalt]dipalladium (COP-OAc) or its enantiomer. This reaction has broad scope, proceeds with predictable high stereoinduction, is accomplished at room temperature using high substrate concentrations and low catalyst loadings, and likely proceeds by a novel mechanism.