Selected examples of the optimization of the alkyl acyloxylations of ynamides^a.

Entry	Catalyst	Conv.b [%]	(Z)-3aab,c [%]	(Z)-3aa  : (E)-3aab	4aab,c [%]
1	Cu(OTf)2	0	—	—	—
2	Zn(OTf)2	0	—	—	—
3	ZnCl2	0	—	—	—
4	Sc(OTf)3	25	<5	75 : 25	10
5	BF3·Et2O	20	12	79 : 21	8
6	TfOH	100	0	—	15
7	Bi(OTf)3	13	0	—	9
8	B(C 6 F 5 ) 3	100	94	>96 : 4	5
9d	B(C6F5)3	13	9	90 : 10	3
10e	B(C6F5)3	82	64	93 : 7	11
11f	B(C6F5)3	96	65	78 : 22	4

^aUnless otherwise noted, the reactions were performed with 1a (0.24 mmol), 2a (Ar¹ = 4-FC₆H₄; 0.2 mmol) and catalyst (5.0 mol%) in toluene (2 mL) at 80 °C for 12 h.

^bDetermined by ¹H NMR spectroscopy of the crude reaction mixture with CH₂Br₂ as an internal standard.

^cNMR yield.

^dThe reaction was run at 60 °C.

^e5 mol% B(C₆F₅)₃ and 5 mol% Mes₃P used.

^fB(C₆F₅)₃ (0.2 mmol) and Mes₃P (0.2 mmol) used.