Table 1.

Reaction optimization^a

Entry	R*SH	Solvent	Yield /%b	D /%c	erd
1	S1	toluene:D2O (3:1)	56	96	48:52
2	S2	toluene:D2O (3:1)	79	90	51:49
3	S3	toluene:D2O (3:1)	42	90	53:47
4	S4	toluene:D2O (3:1)	50	95	58:42
5	S5	toluene:D2O (3:1)	67	94	93:7
6	S6	toluene:D2O (3:1)	49	96	93:7
7	S7	toluene:D2O (3:1)	68	94	92:8
8	S5	toluene:D2O (1:1)	43	97	93:7
9	S5	toluene:D2O (4:1)	71	90	93:7
10	S5	toluene	73	–	88:12
11e	S5	toluene:D2O (3:1)	73	94	93:7
12f	S5	toluene:D2O (3:1)	N.D.	–	–
13g	S5	toluene:D2O (3:1)	N.D.	–	–
14h	–	toluene:D2O (3:1)	N.D.	–	–

er enantiomeric ratio, N.D. Not detected.

^aUnless otherwise noted, all reactions were carried with 1a (0.2 mmol), 2a (0.1 mmol), 4DPAIPN (1 mol%), R*SH (15 mol%), toluene (0.75 mL), D₂O (0.25 mL) under 10 °C for 48 h with irradiation from a 30 W blue LED.

^bIsolated yield of 3a.

^cDetermined by ¹H NMR analysis of the isolated product.

^dDetermined by chiral HPLC analysis.

^eReaction time: 72 h.

^fNo photocatalyst.

^gWithout light irradiation.

^hNo thiol catalyst.