Table 1.

Asymmetric Petasis Reaction Catalyzed by Chiral Diols^a

entry	boronate	R	catalyst	% yieldb	erc
1	6a	H	-	80	-
2	6b	i-Pr	-	<5	-
3	6b	i-Pr	5a	45	60:40
4	6b	i-Pr	5b	65	75:25
5	6b	i-Pr	5c	51	70:30
6	6b	i-Pr	5d	25	59:41
7	6b	i-Pr	5e	70	55:45
8	6b	i-Pr	5f	60	70:30
9	6b	i-Pr	5g	43	64:36
10	6b	i-Pr	5h	67	72:28
11	6b	i-Pr	5i	77	85:15
12	6b	i-Pr	5j	80	87:13
13	6c	CH3	5j	90	90:10
14	6d	Et	5j	81	95.5:4.5
15	6e	n-Bu	5j	77	93:7
16	6a	H	5j	90	57:43

^aReactions were run with 0.15 mmol boronate, 0.10 mmol dibenzylamine, 0.10 mmol glyoxylate, 0.020 mmol catalyst, and 3Å molecular sieves in toluene (0.1 M) for 24 h under Ar, followed by flash chromatography on silica gel.

^bIsolated yield.

^cEnantiomeric ratios determined by chiral HPLC analysis.