Table 2.

Diels-Alder reaction with Catalyst 8 with Excess B(OPh)₃ ^a

Entry	Imine	(S)-VAPOL	(R)-BINOL	B(OPh)3	% Yield 3	% ee 3b
1	1a R = H	10 mol%	—	100 mol%	50	36 (S)
2	1b R = Ph	10 mol%	—	100 mol%	94	90 (S)
3	1b R = Ph	7.5 mol%	—	100 mol%	90	90 (S)
4	1b R = Ph	5 mol%	—	100 mol%	85	90 (S)
5	1b R = Ph	2.5 mol%	—	100 mol%	77	85 (S)
6	1b R = Ph	1 mol%	—	100 mol%	66	82 (S)
7	1b R = Ph	0 mol%	—	100 mol%	25	0
8	1b R = Ph	0 mol%	—	100 mol%	46 c	0
9	1b R = Ph	—	10 mol% d	100 mol%	26	23 (R)
10	1b R = Ph	5 mol%	—	130 mol%	96 e	84 (S)
11	1b R = Ph	5 mol%	—	130 mol%	97 f	77 (S)
12	1b R = Ph	5 mol%	—	150 mol%	96	92 (S)

^aAll reactions were run at 0.2 M in 1 in a 1:1 mixture of toluene and CH₂Cl₂ at −45° for 24 h and with slow addition of 2 equiv of 2 over 3 h by syringe pump. If 2 was added all at once, the % ee of 3 in entry 2 is 88% ee.

^bConfiguration of 3 given in parenthesis.

^cB(OPh)₃ was not heated and evacuated according to the procedure for the preparation of 8.

^dCatalyst prepared with procedure used for 8 except that (R)-BINOL was used.

^eCatalyst was prepared from 30 mol% B(OPh)₃ and then an additional 100 mol% of B(OPh)₃ was added with the imine.

^f0.5 equiv of phenol was added with the imine.