Synthesis of Isoxazolopyridines and Spirooxindoles under Ultrasonic Irradiation and Evaluation of Their Antioxidant Activity

Table 1

Optimization of (±)-CSA catalyst loading in the synthesis of compound 4a.

(±)-CSA (mol%)	Temperature (°C)	Conditions	Time (min)	Yield
—	40	US	300	35
5	40	US	180	52
5	70	US	120	58
10	70	US	120	65
15	70	US	120	71
20	70	US	120	72
20	78	Δ/reflux	360	51

yield.