Optimization of reaction conditions^a.

Entry	Deviation from the standard conditions	Yield (%)
1	None	74 (75)b
2	Ni(acac)2/Zn instead of Ni(cod)2	0
3	Ni(cod)DQ instead of Ni(cod)2	13
4	A gaseous acetylene balloon instead of acetylene saturated solution in THF	18
5	IMes·HCl instead of IPr·HCl	17
6	IAd·HBF4 instead of IPr·HCl	40
7	NaOtBu instead of KOtBu	39
8	DCE instead of THF	21
9	Toluene instead of THF	32
10	10 mol% Ni(cod)2	34
11	1 equiv. acetylene	53
12	2 equiv. Et3SiH	49
13	Room temperature instead of 35 °C	56

^aReaction conditions: 1a (0.3 mmol), saturated solution of acetylene in THF (0.6 mmol), Et₃SiH (1.2 mmol), Ni(cod)₂ (20 mol%), IPr·HCl (40 mol%), KO^tBu (44 mol%), THF (1.5 mL), 35 °C. The yield was determined by ¹H NMR spectroscopy with 4-nitrotoluene as the internal standard.

^bIsolated yield.