Table 5. Catalyst stability screen ^a .

Entry	Catalyst	Conditions	t 1/2
1		(a) Solid rt	15 days
		(b) Solid –20 °C	8 months
		(c) HCl salt, rt	>5 years
		(d) 0.035 M PhMe	7 h
2		Solid, rt	16 h
3		Solid, rt	5 months
4		(a) Solid, rt	>5 years
		(b) 0.035 M	36 h
5		(a) Solid, rt	12 h
		(b) 0.035 M	3 h

^aDecomposition monitored by ¹H NMR; see ESI for method used for each cyclopropenimine.