Asymmetric Diels-Alder Reactions of Unsaturated beta-Ketoesters Catalyzed by Chiral Ruthenium PNNP Complexes

作者：Schotes Christoph; Mezzetti Antonio^*

来源：Journal of the American Chemical Society, 2010, 132(11): 3652-+.

DOI：10.1021/ja910039e

Cyclic alpha-unsaturated beta-ketoesters undergo cycloaddition with di- and trisubstituted butadienes to give tetrahydro-1-indanone derivatives with up to 93% ee in the presence of a ruthenium catalyst formed by activation of [RuCl(2)(PNNP)] with (Et(3)P)PF(6) (2 equiv) (PNNP = (1S,2S)-N,N'-bis[o-(diphenylphosphino)benzylidene]cyclohexane-1,2-diamine). The protocol has been used to prepare the estrone derivative (8R, 13S, 14S)-13-tert-butoxycarbonyl-3-methoxy-7,8,1 2,13,15,16-hexahydro-6H-cyclopenta[a]phenanthren-17(14H)-one as a single diastereoisomer with 85% yield and 99% ee after one crystallization step. Its absolute configuration, which has been determined by X-ray diffraction after reduction to the alcohol and esterification with camphanic chloride, is in agreement with the attack of the diene onto the open enantioface of the beta-keto ester (O-O) in the ruthenium complex [Ru(O-O)(PNNP)](2+), whose X-ray structure has been determined.

• 出版日期2010-3-24