We have reported the Darzens reaction via ammonium ylides to afford 2,3-diaryl epoxides in trans selective manner when electron deficient p-substituted benzylammonium chlorides were used. With the aim of advancing useful methodology based on the new ammonium mediated Darzens reaction, we report the first example of trans selective asymmetric Darzens reaction via chira ammonium ylides to afford enantiomerically enriched 2, 3-diaryl epoxides. The reaction was carried out using amines shown in Chart 1. (Chart 1) The reaction via brucine-p-trifluoromethylbenzyl ammonium ylide afford the corresponding 2, 3-diaryl epoxide in high (98%) yield with moderate diastereo selectivity (17 / 83), and ee (65 %). Enantio and diastereo selectivity were both improved when the reaction were carried out at -20 and -40 degree. (Scheme 1) Next attention was focused on the reaction of a series of substituted benzaldehyde and chiral ammonium ylides. (Scheme 2)
