Process for the asymmetric hydrogenation of beta-ketoesters

摘要

Enantiomerically pure beta -hydroxyesters (I) are prepared by asymmetric hydrogenation of a beta -hydroxyester (II) over a ruthenium complex catalyst (III) containing an optically active bidentate bis-phospholane ligand. Preparation of enantiomerically pure beta -hydroxyesters (I) involves reacting a beta -hydroxyester (II) with hydrogen in presence of a ruthenium complex catalyst of formula (III): LRuX2 (III) X = halo, acetate, allyl, methallyl, 2-phenylallyl, perchlorate, trifluoroacetate, tetrafluoroborate, hexafluoroantimonate, hexafluorophosphate, hexafluoroarsenate or trichloroacetate; L = bidentate bis-phospholane ligand of formula (A) : Y = bridging group providing 1-5C between the two P atoms; R1 = H, 1-6C alkyl, aryl, alkaryl or Si(R2)3; R2 = alkyl or aryl; m = 0 and R3 = OR4; or m = 1 and R3 = H; R4 = as R1.