(+)-CSA Catalyzed Multicomponent Synthesis of 1-[(1,3-Thiazol-2-ylamino)methyl]-2-naphthols and Their Ring-Closure Reaction under Ultrasonic Irradiation

Table 2

Optimization of catalyst loading in the Mannich-type reaction of 2-aminothiazole with benzaldehyde and 2-naphthol using (+)-CSA (see Scheme 2).

CSA (mol%)	Temperature (°C)	Time (min)	Yield (%)
10	25	60	81
10	50	30	87
15	50	30	84
20	50	30	79
5	50	30	90

Isolated yield.