Table 4.

Diels-Alder Reactions of Electron-rich 2′-Hydroxychalcones

entry	2′-hydroxychalcone	product	conditiona	Yield(%)b
1	27: R1=OMe, R2,R3,R4=H	28	A B	68 36
2	29: R1=OAc, R2,R3,R4=H	30	A B	84 55
3	31: R1,R2=OMe, R3,R4=H	32	A	33
4	33: R1,R2=OAc, R3,R4=H	34	A	72
5	35: R1,R3,R4=OMe, R2=H	36	A	18
6	37: R1,R3,R4=OAc, R2=H	38	A	61

^aCondition A: 20/40/120/20 mol% CoI₂/8/ZnI₂/Bu₄NBH₄; condition B: 120/20 mol% ZnI₂/Bu₄NBH₄, see Supporting Information.

^bIsolated yields.