An efficient dipeptide-catalyzed direct asymmetric aldol reaction of equimolar reactants in solid media.

The direct asymmetric aldol reactions of equivalent molar amounts of aldehydes and ketones were carried out at -20 degrees C over alkaline Al2O3 with 20 mol % of Pro-Trp as catalyst and 20 mol % of N-methylmorpholine or 1,4-diazabicyclo[2.2.2]octane as additive. After simple and environmentally friendly work-up, moderate to high isolated yields (up to 95%), good diastereoselectivities (>99:1), and enantioselectivities (up to 98% ee) have been achieved for the reactions of different kinds of ketones with various aldehydes. The catalytic system could be reused without decrease of activity by addition of 10 mol % catalyst and base in the catalytic system. Chirality 22:580-586, 2010. (C) 2009 Wiley-Liss, Inc.