Optimization of the reaction conditions^a.

Entry	Equiv. 2a	Solvent	Additive	Light	Yieldb (%)
1	10	DMA	None	390 nm	65
2	10	DMA	K2CO3	390 nm	82 (75)c
3	10	DMA	DABCO	390 nm	80
4	10	Acetone	K2CO3	390 nm	81
5	10	MeCN	K2CO3	390 nm	88
6	10	DCM	K2CO3	390 nm	85
7	10	MeCN	K2CO3	390 nm	87
8	10	MeCN	K3PO4	390 nm	84
9	10	MeCN	KHCO3	390 nm	90
10	10	MeCN	KHCO3	Dark	<10
11	5	MeCN	KHCO3	390 nm	89
12	2.5	MeCN	KHCO3	390 nm	75
13	5	MeCN	KHCO 3	390 nm	87 d
14	5	MeCN	KHCO3	456 nm	88
15	5	Wet MeCN	KHCO3	390 nm	53d

^aReaction conditions: 0.1 mmol of TT salt 1a, 0.1 mmol of the corresponding additive, indicated amounts of phosphite 2a and 0.1 M in the indicated dry solvent.

^bDetermined by ¹H NMR using 1,3,5-trimethoxybenzene as internal standard.

^cIsolated yield from 0.5 mmol of 1a.

^d30 minutes reaction time.