Table 3. Silver foil-catalyzed mechanochemical cyclopropenation of internal alkynes ^a .

Entry	R1	R2	R3	Product	Yield (%) b
1	CH2CH3	Ph	CH3	19	92
2	(CH2)3CH3	Ph	CH3	20	95
3	Si(CH3)3	Ph	CH3	21	20 c
4	Si(CH(CH2))3	Ph	CH3	22	Trace e
5	Si(Ph)3	Ph	CH3	23	Trace e
6	Ph	Ph	CH3	24	84
7	4-(CH3)Ph	Ph	CH3	25	85
8	4-(Br)Ph	Ph	CH3	26	65
9	3-Thiophenyl	Ph	CH3	27	86
10	CH3	4-(OCH3)Ph	CH3	28	86
11	CH3	4-(C(CH3)3)Ph	CH3	29	84
12	CH3	4-BrPh	CH3	30	89
13	CH3	4-CF3Ph	CH3	31	88
14	(CH2)3CH3	4-BrPh	CH3	32	80
15	(CH2)3CH3	4-(CH3)Ph	CH3	33	79
16	CH3	H	CH2CH3	34	80 c
17	(CH2)3CH3	H	CH2CH3	35	85 c
18	(CH2)3CH3	CO2CH3	CH3	36	Trace e
19 d		Ph	CH3	37	85

^aReation conditions: diazoatate (1.00 eq.), alkyne (5.00 eq,), and silver foil added to a SPEX 8000M mixer/mill (18 Hz) for 16 h.

^bIsolated yields unless otherwise stated.

^cGC yield.

^d4-Octyne was used.

^eRecovered starting material.