Table 1.

Development of the Catalytic Formal Ene Reaction

Entry	Conditionsa	2(%)b	3(%)b	4(%)b,c	5(%)b
1	5 mol%IPrAuCI,5 mol% NaBArF, 65℃	11	8	10	<1
2	10 mol% ZnBr2, 65℃	4	5	1	<1
3	5 mol% In(OTf)3, 65℃	<1	1	<1	<1
4	5 mol% InCI3, 65℃	5	9	<1	<1
5	5 mol% InBr3, 65℃	72	5	6	2
6	5 mol% InI3, 65℃	36	6	7	<1
7	5 mol% InBr3, 5 mol% NaBArF,65℃	40	11	3	<1
8d	5 mol% InBr3,50℃	65	9	3	<1
9	5 mol% MeOH, 8 mol% TMSBr, 65℃	<1	<1	<1	<1
10	5 mol% TfOH, 65℃	<1	<1	<1	<1
Attempted alkenylation of silyl enol ether 6:

^a0.25–0.5 mmol of 1, 1.5 equiv of alkyne, 0.25–0.5 mL of (CH₂Cl)₂, 20–28 h.

^bBased on internal standard and determined by 1H NMR.

^cdr = 1:1.

^d65% isolated yield of 2.