Polystyrene-supported (R)-2-piperazino-1,1,2-triphenylethanol: a readily available supported ligand with unparalleled catalytic activity and enantioselectivity
D. Castellnou, L. Solà, C. Jimeno, J. M. Fraile, J. A. Mayoral, A. Riera, M. A. Pericàs
J. Org. Chem. 2005, 70, 433-438
Abstract: A very active and highly enantioselective catalytic resin, designed for minimal perturbation of the catalytic center by the polymer matrix, has been assembled in two steps from (S)-triphenylethylene oxide, piperazine, and Merrifield resin and tested in the enantioselective ethylation of aldehydes. 1-Arylpropanols of 94-95% ee are obtained in high yield by the use of only 2 mol % of catalytic resin at 0 °C for 4 h.