Table 1.

Diels-Alder reactions of diene 1 with dienophiles 4–6 ^a.

Entry	Dienophile	R1	R2	R3	Reaction Time (h)	Product e (%)
1	4a	CO2Et	CN	H	3.5	7a (73)
2 b	4a	CO2Et	CN	H	20	7a (30)
3 c	4a	CO2Et	CN	H	24	7a (20)
4 d	4a	CO2Et	CN	H	24	7a (20)
5	4b	CO2Et	CN	p-OMe	4.0	7b (50)
6	4c	CO2Et	CN	p-Cl	3.5	7c (60)
7	4d	CO2Et	CN	p-NO2	3.0	7d (80)
8	4e	CO2Et	CN	m-NO2	3.5	7e (55)
9	5a	CN	CN	H	4.0	9a (80)
10	5b	CN	CN	p-OMe	4.5	9b (55)
11	5c	CN	CN	p-Cl	3.0	9c (75)
12	5d	CN	CN	p-NO2	3.0	9d (85)
13	6a	CO2Et	CO2Et	H	5.0	11a (35)
14	6b	CO2Et	CO2Et	p-OMe	6.0	11b (25)
15	6c	CO2Et	CO2Et	p-Cl	5.0	11c (30)

^aAll entries were carried out under IR irradiation at 50 °C and solvent-free conditions, except entries 2–4;

^bUnder thermal (50 °C) and solvent-free conditions;

^cUnder thermal conditions (50 °C) in benzene as the solvent;

^dUnder thermal conditions (50 °C) in THF as the solvent;

^eAfter column chromatography.