Table 3. Base screen for basicity and steric effects ^a .

Base	Δ-1
	% ee b	% yield of (S)-10 c	pKa d
DBU	34	20	24.33
NEt3	72	55	18.82
DIEA	70	38	18.80
	53	33	18.64
	66	43	18.62
DABCO	66	44	18.29
DMAP	57	21	17.95
	40	17	15.8
Collidine	10	8	14.77
	0	21	13–14
TBAF	20	61	?

^aAll reactions were performed using β-nitrostyrene 8 (0.34 mmol, 1 equiv.), diethylmalonate 9 (0.68 mmol, 2 equiv.), and base (0.034 mmol, 0.1 equiv.) in MeCN (1 mL) with 5 mol% catalyst (Δ-1) at room temperature for 24 h.

^bDetermined by chiral HPLC analysis.

^cIsolated yields.

^dpK_a of conjugate acid in acetonitrile.38