Table 2.

Screening of reaction conditions^a

Entry	Change from standard conditions	Yield (%) of 3aab
1	None	71
2	PTH2 instead of PTH1	74 (70)
3	PTH3 instead of PTH1	37
4	PTH4 instead of PTH1	0
5c	Without LiBF4	0
6c	LiPF6 instead of LiBF4	trace
7c	NaBF4 instead of LiBF4	0
8c	MeCN instead of MeCN/DCM	45
9c	DCM instead of MeCN/DCM	53
10c	DMF instead of MeCN/DCM	0
11c	THF instead of MeCN/DCM	39
12c	0 °C instead of 10 °C	31
13c	20 °C instead of 10 °C	69
14c	40 °C instead of 10 °C	65

^a Each reaction was carried out with 1a-1 (0.05 mmol), 2a (0.15 mmol), PTH1 (0.05 mmol) and LiBF₄ (0.05 mmol) in MeCN (0.3 mL) and DCM (0.2 mL) at 10 °C under blue LED irradiation for 18 h^{b 1}.H NMR yields. The number in parentheses is the isolated yield^c .PTH2 (1.0 equiv.) was used.