Table 1. Reaction Optimization^a.

entry	ligand	additives	reductant	yield 3a (%)b	8 (A%)c	9 (A%)c	10 (A%)c	11 (A%)c	12 (A%)c
1	4 + 5d,e	py	Mn	39	17	13	1	3	0
2	4 + 5	py, NaI	Mn	50	7	11	2	5	3
3	4 + 5	py, NaI	Zn	65	3	2	1	8	8
4	4f	py, NaI	Zn	67	8	3	3	6	5
5	4	py, NaI	Zn	75	2	4	2	10	3
6	6	py, NaI	Zn	77	1	1	1	6	3
7	6	py, NaI	Mn	39	25	15	4	3	4
8	7	py, NaI	Zn	73	2	3	1	3	1
9		py, NaI	Zn	11	0.5	0	0	2	2
10	6g	py, NaI	Zn	NR	0	0	0	0	0
11	6h	py, NaI	Zn	53	7	6	4	8	3
12	6i	py, NaI	Zn	49	10	6	6	11	6
13	6	py	Zn	66	2	3	2	6	5
14	6	NaI	Zn	75	3	5	2	3	2
15	6j	py, NaI	Zn	76	2	5	4	5	4
16	6	py, NaI		NR	0	0	0	0	0

^aReactions were assembled on the benchtop on 0.5 mmol scale in 2 mL of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU). The reaction mixtures were heated for 3.5–36 h, and reaction progress was monitored by GC analysis. See Supporting Information for full details.

^bYield of 3a was determined by GC analysis vs an internal standard and is corrected.

^cThe amounts of these products are area % (A%) data.

^dReaction conducted with 5 mol % 4 and 5 mol % 5.

^eReaction run on 1 mmol scale; yield reported is the isolated yield.

^fReaction run with 5 mol % 4/NiI₂·xH₂O/pyridine.

^gReaction run with no nickel.

^hReaction run at 70 °C.

ⁱReaction run at 80 °C.

^jTMSCl and 1,2-dibromoethane (4 μL each) were added sequentially as the last two reagents to the reaction vial.