Table 1 Selected optimization of reaction conditions


Entry	Variations from the ‘initial conditions'	Yield (%)^a
1	No DBU	<10
2	1,1,3,3-tetramethylguanidine instead of DBU	57
3	Triethylamine instead of DBU	65
4	4-dimethylaminopyridine instead of DBU	35
5	Tetramethylethylenediamine instead of DBU	51
6	1,4-diazabicyclo[2.2.2]octane instead of DBU	48
7	CF₃CHN₂ in 1,4-dioxane	69
8	CF₃CHN₂ in DCE	22
9	MeCN instead of 1,4-dioxane	14
10	Diethyl ether instead of 1,4-dioxane	31
11	70 °C	79
12	80 °C	97
13	10 mol% DBU, 80 °C	72

Unless otherwise specified, all reactions were carried out using phenylacetylene 1a (0.3 mmol, 1.0 equiv.) and CF₃CHN₂ 2 (1.2 mmol, 4.0 equiv., 1.5 M in solvents), 20 mol% base (0.06 mmol, 0.2 equiv.), solvent (0.4 mL), 12 h
^aYield of the isolated product 3a after chromatography

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