Table 1 Condition optimization for enantioselective reductive arylative cyclization of 1,6-enynes^a

Entry	Variation from standard conditions	Yield (%) of 3aa^b	ee (%) of 3aa^c
1	None	74	95
2	L1 instead of L8	44	97
3	L2 instead of L8	62	90
4	L3 instead of L8	50	88
5	L4 instead of L8	42	37
6	L5 instead of L8	78	91
7	L6 instead of L8	36	95
8	L7 instead of L8	28	96
9	NiBr₂•glyme instead of Ni(OTf)₂	65	95
10	Ni(OAc)₂•4H₂O instead of Ni(OTf)₂	41	95
11	10 mol% Ni(OTf)₂, 20 mol% (S)-L8	52	95
12	Zn instead of Mn	49	95
13	without HFIP	53	62
14	TFE instead of HFIP	51	90
15	ⁱPrOH instead of HFIP	49	88

^aReaction conditions: 1a (0.2 mmol), 2a (0.3 mmol), Ni(OTf)₂ (15 mol %), (S)-L8 (30 mol %), and Mn (0.6 mmol) in DMA/HFIP (2 mL/2 mL) in a sealed tube at 80 ^oC for 12 hours.
^bIsolated yield after flash chromatography.
^cThe ee values were determined by HPLC on a chiral stationary phase.

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