Table 1. Optimization of the reaction conditions ^a .

Entry	PC (mol%, hν, [nm])	Solvent	DIPEA (eq.)	Additive (eq.)	t [h]	Yield 3a b [%]	Yield 5a c [%]	Yield 8a d [%]
1	A (5, 455)	DMF (dry)	6	—	18	22	15	31
2	B (5, 455)	DMF (dry)	6	—	18	38	8	17
3	B (5, 400)	DMA	6	—	18	54	14	23
4	C (2, 455)	DMA	6	—	18	21	19	43
5	B (5, 400)	DMA	6	LiBF4 (1.5)	18	64	13	23
6	B (5, 400)	DMA	6	LiBF4 (1.5)	2	59	12	28
7	B (5, 400)	DMA	—	LiBF4 (1.5)	18	0	0	0
8	B (5, dark)	DMA	6	LiBF4 (1.5)	18	0	0	0
9	— (400)	DMA	6	LiBF4 (1.5)	15	46	3	15
10	— (400)	DMA	6	LiBF4 (1.5)	4	3	2	6
11	— (455)	DMA	6	LiBF4 (1.5)	15	0	0	0

^aThe reactions were performed using 1 eq. (0.2 mmol) 1a and 2 eq. (0.4 mmol) 2a in 2 mL degassed solvent under nitrogen.

^bYields were determined by GC analysis with 1-naphthol as an internal standard.

^cYields were determined by crude NMR with 1,3,5-trimethoxybenzene as an internal standard.

^dYields were determined by GC analysis with 1-naphthol as an internal standard.