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Table 1 Conditions for the microwave-assisted synthesis of 3-acetylcoumarin (3)

From: Microwave-assisted synthesis and antioxidant properties of hydrazinyl thiazolyl coumarin derivatives

Entry Base Reagents & conditions Yield%
1 Piperidine Solvent-free, 50°C, 5 min -a
2 l-Proline EtOH, 50°C, 5 min 54
3 l-Proline EtOH, 50°C, 10 min 59
4 l-Proline EtOH, 120°C, 1 min 72
5 l-Proline EtOH, 120°C, 2 min 93
6 Piperidine EtOH, 120°C, 1 min 74
7 Piperidine EtOH, 120°C, 10 min 98
8 Piperidine EtOH, 50°C (20 W), 5 min 99
  1. All reactions were carried out using 5 mol% of base under microwave dielectric heating at the given temperature in a sealed tube using a CEM Discover single-mode microwave synthesizer by moderation of the initial magnetron power (20–150 W). Isolated yield after recrystallization (ethanol). a Reaction was halted upon the rapid build-up of pressure.