Table 1.

Optimization of redox co-catalyst

entry	co-cat	mol % co-cat	oxidant	yielda
1	none	0	Air	1%
2	POM-V2b	10	Air	0%
3	Cu(OAc)2	10	air	1%
4	NaNO2	10	air	48%
5	NaNO3	10	air	53%
6	NaNO3	10	nonec	14%
7	NaNO3	10	O2	70%
8	NaNO3	25	O2	91%
9d	NaNO3	25	O2	>95%

^aYields determined by ¹H NMR spectroscopic analysis and represent an average of 2 runs.

^bPOM-V₂ = H₅PMo₁₀V₂O₄₀.

^cN₂ atmosphere.

^d110 °C.