Table 2.

Experimental conditions for compounds (3–6) by conventional and ultrasonic methods.

Compounds	Conventional method		Ultrasonic technique (75–80 °C)
	Time (h)	Yield %	Time (min)	Yield %
3a	7	72	35	86
3b	7	69	35	82
4a	8	74	40	89
4b	8	72	40	87
5a	9	70	45	86
5b	9	72	45	88
6a	8	74	40	89
6b	8	71	40	87