Table 6.

Preparation of oxazoles OX1–15 and 1,2-diketones DK1–13 through trifluoroacetic acid-promoted reaction of β-ketoenamides KE.^a

entry	KE	R1	R2	R3	OX	yield	DK	yield	ref.
1	KE48	Bn	n-Non	Ph	OX1	51%	–		[45]
2	KE51	Bn	t-Bu	2-Th	–	–	DK1	83%	[45]
3	KE52	Bn	Ph	CF3	OX2	74%	–	–	[45]
4	KE53	Bn	Ph	Ph	OX3	48%	–	–	[45]
5	KE54	Bn	Ph	2-Py	OX4	64%	–	–	[45]
6	KE56	PMB	Ph	CF3	OX5	53%	–	–	[45]
7	KE57	2-THP	cPr	cPr	OX6	51%	DK2	<1%	[45]
8	KE58	TMSE	cPr	cPr	OX7	67%	DK3	<1%	[45]
9	KE60	TMSE	t-Bu	Me	OX8	24%	DK4	29%	[45]
10	KE61	TMSE	t-Bu	CF3	OX9	61%	DK5	31%	[45]
11	KE62	TMSE	t-Bu	CH=CH2	–	–	DK6	73%	[43]
12	KE63	TMSE	t-Bu	CH=CH-Me	–	–	DK7	80%	[43]
13	KE64	TMSE	t-Bu	CH=CH-Ph	–	–	DK8	60%	[43]
14	KE65	TMSE	t-Bu	CH=CH-C6H4-NO2	–	–	DK9	55%	[43]
15	KE66	TMSE	t-Bu	CH=CH-2-Fu	–	–	DK10	70%	[43]
16	KE68	TMSE	Ad	cPr	OX10	12%	DK11	65%	[45]
17	KE69	TMSE	Ph	CF3	OX11	98%	--	--	[45]
18	KE70	TMSE	Ph	CH=CH-Me	–	–	DK12	30%b	[43]
19	KE71	TMSE	Ph	CH=CH-Ph	–	–	DK13	33%b	[43]
20	KE72	TMSE	Ph	C≡CH	OX12	57%	–	–	[45]
21	KE74	TMSE	Ph	2-Py	OX13	99%	–	–	[45]
22	KE75	TMSE	Ph	2-Th	OX14	68%	–	–	[45]
23	KE76	TMSE	Ph	Ac	OX15	39%	–	–	[45]

^aAbbreviations: Ad = 1-adamantyl, Py = pyridyl, Fu = furyl, Th = thienyl, Ac = acetyl; all alkenyl substituents are E-configured. ^bIn addition, ca. 30% of a dimeric compound were isolated.