Lindsay Vincent N G, Murphy Rebecca A, Sarpong Richmond
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
Chem Commun (Camb). 2017 Sep 14;53(74):10291-10294. doi: 10.1039/c7cc06367a.
The pronounced beneficial effect of a precise amount of protic additive in an enantioselective Cu-catalysed Diels-Alder reaction is reported. This reaction, which employs a cyclic alkylidene β-ketoester as a dienophile, represents one of the first examples of a transformation where these extremely versatile, though highly unstable reaction partners participate effectively in catalytic asymmetric cycloaddition with a functionalised diene. The cycloadduct was used as an intermediate towards the synthesis of magellanine-type Lycopodium alkaloids featuring a Stille cross-coupling of a highly congested enol triflate and a unique Meinwald rearrangement/cyclopropanation sequence.
据报道,在对映选择性铜催化的狄尔斯-阿尔德反应中,精确量的质子添加剂具有显著的有益效果。该反应使用环状亚烷基β-酮酯作为亲双烯体,是这些极其通用但高度不稳定的反应伙伴有效参与与官能化二烯的催化不对称环加成反应的首批转化实例之一。环加成产物被用作合成麦哲伦型石松生物碱的中间体,该合成过程具有高度拥挤的烯醇三氟甲磺酸酯的施蒂勒交叉偶联以及独特的迈恩瓦尔德重排/环丙烷化序列。