Laboratoire de Chimie Organique Bio-organique Réactivité et Analyse (COBRA), CNRS UMR 6014 & FR 3038, Université et INSA de Rouen, Rue Tesnière, Mont-Saint-Aignan 76130-F, France.
J Org Chem. 2010 Nov 19;75(22):7704-16. doi: 10.1021/jo101585t. Epub 2010 Oct 19.
In the present work, enantioselective protonation of silyl enol ethers is reported by means of a variety of chiral nitrogen bases as catalysts, mainly derived from cinchona alkaloids, in the presence of various protic nucleophiles as proton source. A detailed study of the most relevant reaction parameters is disclosed allowing high enantioselectivities of up to 92% ee with excellent yields to be achieved under mild and eco-friendly conditions. The synthetic utility of this organocatalytic protonation was demonstrated during the preparation of two homoisoflavones 4a and 4b, isolated from Chlorophytum Inornatum and Scilla Nervosa, which were obtained with 81% and 78% ee, respectively.
在本工作中，通过各种手性氮碱作为催化剂，主要来源于金鸡纳生物碱，在各种质子亲核试剂作为质子源的存在下，报道了硅基烯醇醚的对映选择性质子化。详细研究了最相关的反应参数，在温和且环保的条件下，以优异的产率实现了高达 92%ee 的高对映选择性。这种有机催化质子化的合成实用性在从 Chlorophytum Inornatum 和 Scilla Nervosa 中分离得到的两个同型异黄酮 4a 和 4b 的制备中得到了证明，它们的ee 值分别为 81%和 78%。
