Table 1.

Comparison of catalyst efficiency and chemoselectivity^a

Entry	Cat.	Solvent	Temp. (°C)	Conv. (%)b	2a (%)b	3a (%)b	4a (%)b
1	Ir1	MeOH	25	40	28	12	<1
2	Ir1	MeOH	37	>99	93	7	<1
3	Ir2	MeOH	37	>99	95	5	<1
4	Ir3	MeOH	37	96	92	4	<1
5	Ir4	MeOH	37	>99	98	2	<1
6	Ir5	MeOH	37	>99	95	5	<1
7	Ir6	MeOH	37	>99	90	10	<1
8	Ir7	MeOH	37	>99	93	7	<1
9	Ir8	MeOH	37	>99	96	4	<1
10	Ir9	MeOH	37	>99	96	4	<1
11	Ir10	MeOH	37	80	12	67	<1
12	Ir11	MeOH	37	71	11	59	<1
13	Ir12	MeOH	37	50	21	29	<1
14c	Ir1	MeOH	37	>99	81	<1	18
15c	Ir1	EtOH	37	>99	52	<1	48
16c	Ir1	iPrOH	37	>99	62	<1	38
17c	Ir1	THF	37	35	10	25	<1
18c	Ir1	MeCN	37	>99	96	4	<1
19	none	MeOH	37	<1	<1	<1	<1

^aReagents and conditions: 1a (100 μmol), Ir1 (1.0 μmol), HCOONH₄ (200 μmol), solvent (0.5 mL), 15 h.

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

^c10 equiv. of HCOONH₄ was used.