Table 1.

Development of an Enantioselective CO₂-Capture Reaction using a Homoallylic Alcohol

entry	ligand (base)	acida	notesb	yieldc	ee (%)d
1	none	–	–	0%	–
2	none	–	NaHe	16%	–
3	none	–	NaH (THF)e	25%	–
4	DMAP (5)f	–	–	trace	–
5	DBU (6)f	–	–	trace	–
6	TBD (4)f	–	–	11%	–
7	TFAf	–	–	6%	–
8	3f	–	–	4%	–
9	PBAM (7)	–	–	18%	39
10	StilbPBAM (8)	–	–	33%	36
11	8	–	MS	35%	60
12	8	HOTf	MS	62%	74
13	8	H2NTf	MS	52%	62
14	8	F6C3(SO2)2NH	MS	70%	86
15	8g	HNTf2	MS, 0.4 M	95%	91
16	8	HNTf2	MS, 0.2 M	51%	89
17	8	HNTf2	MS, 0.1 M	10%	79
18	5f	–	–	trace	–
19	4f	–	MS	30%	–
20	6f	–	MS	13%	–
21	6f	½ HNTf2	MS	4%	–

^aCatalyst prepared as the 1:1 acid salt, except entry 21.

^bMS denotes molecular sieves 4A, employed at a concentration of 1 g/mmol relative to the alcohol.

^cIsolated yield.

^dEnantiomeric excess (ee) determined by HPLC using a chiral stationary phase. Reactions are 0.4 M toluene unless otherwise noted.

^eReaction temp = 0 °C. 3-Methyl-3-buten-1-ol was converted in 60% yield under identical conditions.

^f20 mol % catalyst employed.

^g5 mol % catalyst employed, with results analogous to those using 10 mol % catalyst.