An Efficient One-Pot Multicomponent Synthesis of 4-Aza-Podophyllotoxin Derivatives in Ionic Liquid

Table 1

Different polar and nonpolar used solvents, for the synthesis of 4i ^a under reflux conditions.

Entry	Solvent	Time (min)	Yield (%)^b
1	MeOH	120	72
2	EtOH	120	75
3	1,4-Dioxane	120	60
4	DMF	120	70
5	Toluene	120	65
6	[bmim][triflate]	30	90
7	[bmim]OH	30	75
8	[bmim]PF6	30	88
9	[bmim]BF4	30	83
10	[bmim]Br	30	80

aReaction conditions: 4-bromobenzaldehyde 1d (1 mmol), dimedone 2b (1 mmol), and 4-(4-methylphenylamino)furan-2(3H)-one 3d (1 mmol), p-TSA (20 mol%).
bIsolated yields.