Comparison of the catalytic procedure with other methods for the direct synthesis of N-aryl or alkyl nitrones.

Entry	Reaction conditions	Time (h)	Yield (%)
1		2.5–9	15–89 (ref. 25)
2		3.5–8	50–80 (ref. 26)
3		3–8	40–75 (ref. 27)
4		2–8	50–97 (ref. 28)
5		0.4–0.58	85–91 (this work)