Table 1.

Optimization of the synthesis of 4a.

Entry	1/2a/3a	Reaction Conditions	Yield (%)
1	1.0/1.0/1.0	EtOH, rt, 20 h	33
2	1.0/1.0/1.0	EtOH, reflux, 2 h	75
3	1.0/1.0/1.0	EtOH, MW, 130 °C, 5 min	56
4	1.0/1.0/1.0	EtOH, MW, 150 °C, 10 min	69
5	1.0/1.5/1.5	EtOH, MW, 150 °C, 15 min	76
6	1.0/1.0/1.0	DCE, MW, 150 °C, 10 min	57
7	1.0/1.5/1.5	DCE, MW, 150 °C, 10 min	94