Ruthenium complexes with a chiral, bidentate phosphinoxazoline ligand for the enantioselective transfer hydrogenation of prochiral ketones

摘要

Chiral ruthenium complexes of formula RuX1X2L1L2 (I) are new. X1, X2 = anion (from halogen, 1-10 C carboxylic acid (optionally substituted by 1-3 Cl or F), methane sulphinic acid or trifluoromethane sulphinic acid; or X1+X2 = dianion of a 1,3-, 1,4- or 1,5-dicarboxylic acid; L1 = 5-6 membered cyclic ether, 5-8 C cyclic olefin, aromatic compound (optionally substituted by 1-3 alkyl), CO, PF3, isobutene or PR1R2R3; L2 = a bidentate chiral ligand of formula (III); R1R3 = alkyl, cycloalkyl, or aryl (optionally substituted by 1-3 1-4 C alkyl or 1-4 C alkoxy); R4 = alkyl, cycloalkyl or aryl (optionally substituted by 1-3 alkyl, alkoxy or halo); R5 = H or as for R4; or PR4R5 = a saturated 5-7 C ring, optionally condensed with 1 or 2 aryl; R6 = alkyl (optionally substituted by one or more OH, SH, NH, COOH, aryloxy, alkoxy, arylthio, alkylthio, acyloxy, alkoxycarbonyl, acylamino, aralkyl, heteroaralkyl, aryl or heteroaryl); R7 = H, alkyl, aryl or aralkyl; R8, R9 = H, 1-4 C alkyl or 1-4 C alkoxy; or R8+R9 complete cycloalkyl or aryl; provided that the absolute configuration of C atoms carrying R6 and R7 is independently (S) or (R).