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

BMC Chemistry

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

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

^† 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.

ISSN: 2661-801X