126260-21-7Relevant articles and documents
A New Aysmmetric Synthesis of Cyanohydrins and Oxygen-Functionalized Derivatives: Stereoselective Addition of Cyanide to Chiral Rhenium Aldehyde and Ketone Complexes of the Formula 5-C5H5)Re(NO)(PPh3)(O=CRR')>+BF4-
Dalton, Dennis M.,Garner, Charles M.,Fernandez, Jesus M.,Gladysz, J. A.
, p. 6823 - 6829 (2007/10/02)
Reactions of racemic and optically active ? aldehyde complexes 5-C5H5)Re(NO)(PPh3)(η2-O=CHR)>+BF4- (1; R = a, CH3; b, CH2CH3; c, CH(CH3)2; d, CH2C6H5; e, C6H5) with (CH3CH2)4N+CN- (CH2Cl2, -80 deg C) to give cyanohydrin alkoxide complexes (η5-C5H5)Re(NO)(PPh3)(OCH(CN)R) (3a-e, 78-95percent) in 89-53percent de.Subsequent reactions of (+)-(RS)-3a-e with (-)-(R)-C6H5(CH3O)(F3C)CC(=O)Cl (MTPA-Cl) and DMAP in C6H6 give optically active esters MTPA-OCH(CN)R (85-96percent, 90-56percent de).Analogous reactions of racemic ?-methyl ketone complexes 5-C5H5)Re(NO)(PPh3)(η1-O=C(CH3)R)>+BF4- (2; R = a, CH3; b, CH2CH3; c, CH(CH3)2; d, C(CH3)3; e, C6H5) and (CH3CH2)4N+CN- give alkoxide complexes (η5-C5H5)Re(NO)(PPh3)(OCCH3(CN)R) (5a-e, 60-88percent) in 71-99percent de.A similar reaction of 2e and (CH3)3SiCCLi gives (η5-C5H5)Re(NO)(PPh3)(OCCH3(CCSi(CH3)3)C6H5) (88percent) in 94percent de.Mechanisms of diastereoselection are briefly discussed.
