Table 1. Optimization for the Synthesis of 4 and 5.

entry	solvent	t (°C)	time/h	(4a/5a) yield (%)a
1	MeOH	rt	24	33/41
2	EtOH	rt	24	62/19
3	DMF	rt	24	trace/trace
4	DCE	rt	24	57/13
5	CH3CN	rt	24	48/23
6	toluene	rt	24	72/<5
7	THF	rt	24	62/10
8	1,4-dioxane	rt	24	74/<5
9	MeOH	60	1	39/34
10	1,4-dioxane	60	1	68/<5

^aIsolated yield.