Table 1. Reaction of N-phenylthiourea with methyl 4-bromocrotonate ^a .

S. no.	Solvent	Yield (%)
1	HFIP	90
2	2,2,2-Trifluroethanol	74
3	CH2Cl2	50
4	CHCl3	55
5	CH3OH	60
6	CH3CH2OH	50
7	Isopropanol	65
8	1-Propanol	55
9	2-Butanol	60
10	CH3CN	48
11	THF	40
12	Acetone	NR
13	DMF	NR
14	DMSO	NR
15	H2O	NR
16	Neat	NR
17	HFIP : MeOH (1 : 1)	64

^aReaction conditions: substrate (1.0 mmol), Michael acceptor (1.1 mmol), sodium acetate (1.1 mmol), and HFIP solvent (5 mL).