Table 1.

Development and optimization for C-3 imidazo[1,2-a]pyridine acetylation.

Entry	Catalyst	Eqv Cat	Eqv Ac2O	Solvent	T[°C]	Time (h)	Yield (%)
1	/	/	2	Acetonitrile	80	6	Trace
2	FeSO4 7H2O	0.10	2	Acetonitrile	80	6	NR
3	FeCl2	0.10	2	Acetonitrile	80	6	NR
4	SeO2	0.10	2	Acetonitrile	80	6	NR
5	La(NO3)3 6H2O	0.10	2	Acetonitrile	80	6	NR
6	ZrCl4	0.10	2	Acetonitrile	80	6	16
7	La(0Tf)3	0.10	2	Acetonitrile	80	6	32
8	A1C13	0.10	2	Acetonitrile	80	6	40
9	A1C13	0.25	2	Acetonitrile	80	6	45
10	A1C13	0.50	2	Acetonitrile	80	6	53
11	A1C13	0.75	2	Acetonitrile	80	6	57
12	A1C13	1.00	2	Acetonitrile	80	6	55
13	A1C13	0.25	2	Acetonitrile	80	12	60
14	A1C13	0.25	2	Benzene	80	12	NR
15	A1C13	0.25	2	Xylene	80	12	NR
16	A1C13	0.25	2	Toluene	80	12	NR
17	A1C13	0.25	2	DMA	80	12	Trace
18	A1C13	0.25	2	DCE	80	12	NR
19	A1C13	0.25	2	Dry DMF	80	12	NR
20	A1C13	0.25	2	Dry THF	80	12	NR
21	A1C13	0.25	2	Dry Dioxane	80	12	NR
22	A1C13	0.25	2	Dry DMSO	80	12	NR
23	A1C13	0.25	2	NMP	80	12	NR
24	A1C13	0.25	Neata	Ac2O	80	12	63
25	A1C13	0.25	Neata	Ac2O	100	12	75
26	A1C13	0.25	Neata	Ac2O	130	12	78
27	A1C13	0.25	Neata	Ac2O	160	16	99

NR = No Reaction.

^aCompleted in 0.33 M acetic anhydride solution.