Table 1. Studies of the promotion effect of amides, their derivatives, amines and amine alcohols in the Cα-heteroarylation of tetrahydrofuran with isoquinoline and the optimization of the reaction conditions ^a .

Entry	Oxidant	Additive	1a (equiv.)	Yield b
1	(NH4)2S2O8	—	20	14%
2	(NH4)2S2O8	A1	20	77%
3	(NH4)2S2O8	A2	20	15%
4	(NH4)2S2O8	A3	20	24%
5	(NH4)2S2O8	A4	20	50%
6	(NH4)2S2O8	A5	20	53%
7	(NH4)2S2O8	A6	20	55%
8	(NH4)2S2O8	A7	20	70%
9	(NH4)2S2O8	A8	20	7%
10	(NH4)2S2O8	A9	20	15%
11	(NH4)2S2O8	A10	20	80%
12	(NH4)2S2O8	A11	20	82%
13	(NH4)2S2O8	A12	20	5%
14	(NH4)2S2O8	A13	20	88%
15	(NH4)2S2O8	A13	20	42% c
16	(NH4)2S2O8	A13	20	82% d
17	(NH4)2S2O8	A13	20	75% e
18	(NH4)2S2O8	A13	10	82%
19	(NH4)2S2O8	A13	10	80% f
20	(NH4)2S2O8	A13	5	60% f
21	(NH4)2S2O8	A13	5	67% f , g

^aConditions employed 1a (2.5–10.0 mmol), 2a (0.5 mmol), oxidant (1.5 mmol), additive (1.0 mmol), 40 °C, 24 h, and a solvent mixture (1.5 mL, MeCN : H₂O = 1 : 1), unless otherwise noted.

^bThe yields were determined using ¹H NMR with CH₂Br₂ as an internal standard.

^cPerformed with (NH₄)₂S₂O₈ (1 equiv.).

^dPerformed with A13 (1 equiv.).

^ePerformed with A13 (0.5 equiv.).

^fWater (1.5 mL) was used as the solvent.

^gPerformed on a 1 g scale.