Table 2: Asymmetric addition of diethylzinc to aldehydes in the presence of 2a.


EntryArLigand 2Yield (%)be.e. (%)c

1Ph2a8650
2dPh2a8852
3Ph2b757
4Ph2c806
5ePhSilica gel-supported 2a5925
6o-MeOC6H42a90 (86)f57 (54)f
7eo-MeOC6H4Silica gel-supported 2a6534
8p-MeC6H42a8243
9p-ClC6H42a9050

Reactions were carried out in hexane at room temperature using 2 equiv. of Et2Zn unless otherwise noted. Absolute configuration was assigned by the elution order from chiral column. bDetermined by GC analysis. cDetermined by HPLC analysis using Chiralcel OD-H column (3% of 2-propanol in hexane, 0.5 mL/min). d10 mol% of ligand was used. eSee [41]. fThe catalyst was reused three times.