Table 1.

Optimization of the Oxysulfenylation^a

entry	change from standard conditions	yield (%)	ee (%)
1	L1	68
2	none (first optimal)	86	90
3	L3	73	−90
4	DCE, 105 °C	70	91
5b	15 mol % [Cu] (second optimal)	87	90
6c	10 mol % [Cu]	59	ND
7	75 mol % Ph2S2	60d	ND
8	dry air, no K2CO3	42 (47)e	91
9	100% O2, no K2CO3	14 (49)e	ND
10	no oxidant	21 (70)e	ND
11	1 mmol scale	62	85

^aReaction run on 0.1 mmol of 1a, in PhCF₃ (0.1 M w/r 1a) in a sealed tube in a 120 °C oil bath under argon unless otherwise noted. The isolated yield is reported following flash chromatography on silica gel. Enantiomeric excess was measured by chiral HPLC.

^b18 mol % L2 was used.

^c13 mol % L2 was used.

^dConversion determined by analysis of crude ¹H NMR. Remainder is substrate 1a.

^eIsolated recovered substrate 1a in parentheses. ND = not determined.