Microwave-Assisted Three-Component “Catalyst and Solvent-Free” Green Protocol: A Highly Efficient and Clean One-Pot Synthesis of Tetrahydrobenzo[b]pyrans
Scheme 3
Synthesis of various 4H-benzo[b]pyran derivatives. Reaction conditions: 1 mmol of 1, 1 mmol of 2, and 1 mmol of 3 under microwave irradiation at 80°C for 7 min. All are isolated yields. mmol of aldehyde, 1 mmol of 2, and 1 mmol of 4-hydroxycoumarin under microwave irradiation at 80°C for 7 min.