An Efficient, Clean, and Catalyst-Free Synthesis of Fused Pyrimidines Using Sonochemistry

Table 1

Effect of various solvents in the synthesis of 4a under conventional conditions and ultrasonic irradiations.

Entry	Solvent	Conventional method		Sonochemical method
		Time (min)	Yield (%)^a	Time (min)	Yield (%)^a
1	Ethylene glycol	180	90^b	25	95^c
2	AcOH	180	86	29	90
3	DMF	210	82	29	88
4	EtOH	220	84	30	88
5	H2O	240	78	41	83
6	Acetone	240	70	42	76
7	CHCl3	270	66	47	70
8	CH3CN	300	60	50	65

Isolated yield.
^bReflux temperature.
^c65°C.