作者:Wanqing Wu、Long Min、Lizhi Zhu、Chi-Sing Lee
DOI:10.1002/adsc.201000927
日期:2011.5.9
A highly enantioselective catalytic Diels–Alder (DA) cycloaddition of 2H‐pyran‐2,5‐diones (synthon of 5‐hydroxy‐2‐pyrones) has been developed with a Cinchona‐derived thiourea as the catalyst. The conditions were optimized by using 0.2 equiv. of the catalyst and 0.1 equiv. of formic acid in 2‐propanol at room temperature, which afforded the DA products in yields of up to 90% (exo/endo=5.5:1, 98% ee)
已开发了一种高度对映选择性的Diels-Alder(DA)环加成2 H-吡喃-2,5-二酮(5-羟基-2-吡喃酮的合成子),并以金鸡纳衍生的硫脲为催化剂。通过使用0.2当量优化条件。催化剂的量和0.1当量 在室温下,在2-丙醇中加入20%的甲酸,以反式-β-硝基苯乙烯衍生物作为亲二烯体,可获得高达90%的DA产物(外/内= 5.5:1,98%ee)。研究了双功能催化剂的结构/活性关系以及亲双烯体的空间,电子和氢键性质的影响。