Table 1.

Optimization of Alkynylation Conditions^a

entry	base	CuZ	solvent	alkyne equiv, X	yield (%)b
1	KHMDS	CuI	pyr	1.0, I	44
2	KHMDS	CuI	pyr	1.0, Br	48
3	KHMDS	CuI	pyrc	1.0, Cl	23
4	KHMDS	CuI	DMF	1.0, Br	26
5	n-BuLi	CuI	pyr	1.0, Br	0
6	n-BuLi	CuI	DMSO	1.0, Br	20
7	n-BuLi	CuTCd	DMSO	1.0, Br	24
8	KHMDS	CuI	pyr	0.6, Br	40e
9	KHMDS	CuI	pyr	2.0, Br	67f
10	KHMDS	CuCN	pyr	2.0, Br	41
11	KHMDS	CuI	tol, diamineg	2.0, Br	40
12	KHMDS	CuI	pyr	5.0, Br	28h

^aAll reactions were carried out at rt for 20 h unless otherwise indicated. Concentration of 8a (0.200 g scale) was 0.15 M. Alkynes were added as benzene solutions.

^bIsolated yields of products purified by column chromatography.

^cReaction at 75 °C.

^dCopper(I) thiophene-2-carboxylate.

^eYield based on 1-bromo-2-phenylethyne.

^fYield improved to 76% when scale increased to 2.0 g of 8a.

^g4.0 equiv of diamine ligand MeN(H)CH₂-CH₂N(H)Me.

^hReaction for 90 h.