Microwave-assisted, highly enantioselective addition of diethylzinc to aromatic aldehydes catalyzed by chiral aminonaphthols

New optically active aminonaphthols were obtained by condensation of 2-naphthol, benzaldehyde and (R)-(+)-1-(1-naphthyl)ethylamine or (R)-(+)-1-(2-naphthyl)ethylamine. Their N-methylated derivatives were also synthesized. The new aminonaphthols 2, 4, 5 and 7 were found to catalyze the enantioselective ethylation of aryl aldehydes to 1-aryl-1-propanots (up to 92% ee). The reactions were accelerated greatly by microwave irradiation. (C) 2008 Elsevier Ltd. All rights reserved.