Table 1.

Reaction optimization

Entry	time (h)	3 (eq)	Lamp (nm)	Solvent	2ah %	4ah %	5h %
1a,f	3	7.5	390	EtOAc	6	15	59
2 a,f	3	7.5	390	CH3CN	5	16	57
3 b,f	3	7.5	390	EtOAc	7	29	40
4 a,f	3	7.5	390	CH3CN	6	26	37
5 g	3	7.5	390	neat	18	38	23
6 f	3	15	390	neat	6	47	28
7 g	3	7.5	370	neat	44	26	19
8 g	3	7.5	427	neat	40	30	17
9 g	3	7.5	440	neat	58	21	11
10 g	3	7.5	456	neat	76	12	7
11 g	3	7.5	525	neat	98	0	0
12 e,g	3	7.5	--	neat	99	0	0
13 c,g	3	7.5	390	neat	20	33	20
14 d,g	3	7.5	390	neat	22	37	22
15 c,g	16	7.5	390	neat	--	36	8
16 d,g	16	7.5	390	neat	--	36	9
17 g	16	7.5	390	neat	--	48	9

^a0.65 mL.

^b0.172 mL.

^cno Aldrithiol.

^dno freeze-pump-thaw.

^e60 °C and shielded from light.

^f0.2 mmol imine.

^g0.4 mmol imine.

^hyield based on Q¹HNMR analysis with 1,3,5-trimethoxybenzene internal standard