Table 2.

Base optimization for the synthesis of 1.

Entry	Base	Yield (%)-drya	Yield (%)-not dryb	Yield (%)-dioxane/water 4:1
1	Li3PO4	0	4	19
2	Na3PO4	39	41	75
3	K3PO4	51	17	11
4	NaF	14	4	37
5	KF	51	24	54
6	KHF2	76	25	26
7	CsF	69	8	58
8	NBu4F	ND	12	14
9	Li2CO3	0	4	54
10	Na2CO3	33	7	35
11	K2CO3	26	19	25
12	Cs2CO3	15	9	10
13	NaOH	NP	36	5
14	KOH	NP	7	18
15	Et3N	4	9	9
16	Pyridine	0	4	10
17	DBU	NP	6	8
18	None	-	-	10

Note: Reaction conditions: PyFluor (0.3 mmol), 2-thiopheneboronic acid pinacol ester (0.45 mmol), Pd(dppf)Cl₂ (0.03 mmol), base (0.9 mmol), biphenyl (internal standard, 0.06 mmol), and solvent mixture (1 mL in a closed 1 dram vial).

^aDioxane was degassed by three cycles of freeze–pump–thaw and dried under molecular sieves (10% v/w) for 48 h before using it.

^bSolvent was used as purchased. Yield calculated using biphenyl as internal standard (HPLC/UV). NP = not performed.