Table 2. Optimization of Base and Solvent in the Coupling of 1 and 2^a.

			3 (yield, %)b
entry	base	solvent	t = 2 h	t = 18 h
1	DABCO	MTBE	42	54
2	DABCO	DCM	25	35
3	DABCO	MeOH	27	35
4	DABCO	EtOH	26	40
5	DABCO	THF	46	72
6	DABCO	1,4-dioxane	40	74
7	DABCO	ACN	67	82
8	DABCO	DMF	42	62
9	DABCO	NMP	26	40
10	DABCO	3 wt % PTS in H2O	33	50
11	DABCO	DMSO	91	100
12	none	DMSO	0	0
13	NaOAc	DMSO	86	100
14	KOH	DMSO	50	100
15	K2CO3	DMSO	50	100
16	K3PO4	DMSO	51	100
17	KHCO3	DMSO	26	43
18	Cs2CO3	DMSO	0	0
19	TBAF	DMSO	0	0
20	t-BuNH2	DMSO	86	89
21	iPr2NH	DMSO	100	100
22	Hunigs’ base	DMSO	84	100
23	TMP	DMSO	100	100
24	Et2NH	DMSO	15	56
25	Et3N	DMSO	53	58
26	pyrrolidine	DMSO	27	100
27	piperidine	DMSO	42	100
28	morpholine	DMSO	20	58
29	DBU	DMSO	2	10

^aReaction conditions: 1 (0.5 mmol), 2 (0.8 mmol), P2 (0.025 mmol, 5 mol %), base (1.0 mmol), solvent (2.5 mL), rt for 18 h under argon atmosphere.

^bYield was determined by LC/MS with pyrene as internal standard.