Table 1: DABCO catalyzed synthesis of 4a in different reaction conditions.

EntrySolvent /°CTime/hYielda/%

1EtOHReflux285
2CH2Cl2Reflux654
3CH3CNReflux473
4THFReflux462
5H2OReflux1.587
61000.594
760265
880176
9 1200.592
10b100265
11c1000.595

Isolated yield.
b1 mol% of catalyst was used.
c10 mol% of catalyst was used.