Table 2. Optimizations of Various Solvents for [3 + 2] Cycloaddition Reaction Using K₃PO₄ Base^a.

entry	solvent	temperature (°C)	time (h)	oxazoline yield (%)c	oxazole yield (%)c
1	DMF	60	6	0	0
2	DMSO	60	6	0	0
3	THF	60	6	95	0
4	CH3CN	60	6	95	0
5	CHCI3	60	6	50	40
6	IPA-H2O	60	4	10	80
7	IPA	rt	6	94	0
8	EtOH	60	1.5	0	92
9	IPA	60	1	0	95
10	IPA	MWb, 65	0.13	0	96

^aReaction was performed using 1a (1.18 mmol), 2a (1.18 mmol), and K₃PO₄ (2.36 mmol).

^bMicrowave reactions were carried out in a microwave model no. CATA R (Catalyst Systems, Pune) at 65 °C using a power of 350 W.

^cYield of the isolated product.