Table 1: Screening of bases, solvents, reaction time and yield for the synthesis (6a)a.

Entry Base Solvent Time (min) Yieldb (%)
1 Diethylamine Ethanol 120 50
2 Diethylamine Methanol 130 30
3 Diethylamine Acetic acid 150 35
4 Diethylamine DCM 110 40
5 Diethylamine Toluene 140 30
6 Triethylamine Ethanol 100 65
7 Triethylamine Methanol 110 40
8 Triethylamine Acetic acid 130 30
9 Triethylamine DCM 120 45
10 Triethylamine Toluene 125 35
11 Potassium carbonate Ethanol 30 90
12 Potassium carbonate Methanol 40 80
13 Potassium carbonate Acetic acid 60 80
14 Potassium carbonate DCM 50 85
15 Potassium carbonate Toluene 70 75

a All the reaction was carried out in 1:1.2 molar amounts of each compound in 1 mL of solvent.
b Isolated yield.