Table 2.

Asymmetric Epoxidation of 1,1-Disubstituted Terminal Olefins with Ketone 3d^a

entry	substrate	yield (%)b	ee (%)	config.e
1	R = Me	60	62c	(+)−(S)13a
2	R = Et	71	78d	(+)–(S)13a
3	R = n-Pr	90	75d	(+)
4	R = i-Bu	54	74d	(+)
5	R = c-C6H11	62	77c	(+)
6	R = t-Bu	43	86d	(+)
7	X = H	71	84d	(+)
8	X = p-i-Pr	51	82c	(+)
9	X = p-MeO	94	84c	(+)
10	X = p-F	78	74d	(+)
11	X = p-Br	68	78d	(+)
12	X = m-Me	57	82c	(+)
13	X = m-F	74	81d	(+)
14	X = o-F	72	88d	(+)
15		51	66c	(−)–(S)13b
16	n = 1	93	77c	(+)–(R)13c
17	n = 2	47	72c	(+)
18	n = 3	62	74c	(+)
19	R = Me	76	87c	(+)–(S)13a
20	R = Et	85	87d	(+)
21	R,R = (CH2)4	86	88d	(+)–(S)13a
22		78	60d	(+)

^aAll epoxidations were carried out with the olefin (0.2 mmol), ketone 3d (0.06 mmol), Oxone (0.32 mmol), and K₂CO₃ (1.344 mmol) in 1,4-dioxane (3 mL), and buffer (0.1 M K₂CO₃/AcOH, pH 9.3; 2 mL) at −10 °C for 2 h (4 h for entries 6, 11, 13, and 14).

^bIsolated yield except entry 7 which is crude yield.

^cThe ee was determined by chiral HPLC (Chiracel OD column).

^dThe ee was determined by chiral GC (B-DM column).

^eThe absolute configurations were determined by comparing the measured optical rotations and HPLC trace with reported ones.