Table 4.

Exploration of Various Enals^a

entry	R3	product	yield (%)	dr	ee (%)
1b	2b	3n	62	11/1	66
2c	4-NO2-C6H4 2c	3o	99	14/1	93
3d	4-Br-C6H4 2d	3p	58	17/1	91
4d	Ph 2e	3q	48	20/1	90

^aConditions: aldehyde 2, 0.2 mmol; 1a, 0.1 mmol; A2, 20 mol%; C4; 20 mol%; solv., 0.8 mL; all reactions were carried out under Ar in the presence of 4A MS at 0 °C. The trans/cis ratio is determined by ¹H NMR prior to purification. The ee’s are determined by chiral HPLC.

^b15 h in acrylonitrile.

^c36 h in CH₂Cl₂.

^d66 h in CH₂Cl₂.