Microwave-Promoted One-Pot Syntheses of Coumarin Dyes

Abstract

To one pot synthesis of coumarins with benzimidazol or benzoxazol moieties, three different microwave irradiations based procedures are reported here which take place within a few minutes. In spite of fairly well yield of the products using solvent free procedures, 25–30% further yields were achieved within 3 minutes at 110 °C using 2 mL n-pentanol as solvent.

Keywords:

• Benzimidazol
• benzoxazol
• microwave irradiation
• solvent free

Notes

Note. The 900 W was used as microwave power, and the reported times and temperature were compared with literature (lit.).

Note. The 900 W was used as microwave power, and the reported times and temperature were compared with literature (lit.).

Note. The 900 W was used as microwave power, and the reported times and temperature were compared with literature (lit.).

^a λ _abs: maximum absorption wavelength; ε: corresponding molar absorption coefficient; λ _em: maximum emission wavelength.

^b Maximum excitation wavelength was measured at 230 nm.