Synthesis of thiophene derivatives 3a–3j^a.

Entry	Compd	Ar	R	Yield (%)b
1	3a	p-CH3OC6H4	Bn	62
2	3b	m-CH3OC6H4	Bn	60
3	3c	o-CH3OC6H4	Bn	60
4	3d	p-CH3C6H4	Bn	55
5	3e	p-ClC6H4	Bn	63
6	3f	p-BrC6H4	Bn	55
7	3g	p-CH3C6H4	H	60
8	3h	p-CH3OC6H4	Me	68
9	3i	p-CH3OC6H4	CH2CH2Ph	58
10	3j	p-CH3OC6H4	CH2C6H4OH-p	66

^aReaction conditions: 1. ArCHO (2.0 mmol), CH₂(CN)₂ (2.0 mmol), α-amino acid ethyl ester (2.0 mmol), 1,3-thiazolidinedione (2.0 mmol), Et₃N (3.0 mmol), 40–50 °C, 6 h; 2. DDQ (2.2 mmol), 60 °C, 4 h.

^bIsolated yields.