Screening of conditions and promoters for a dienamine-catalyzed asymmetric pyrone Diels–Alder reaction of 22 and 23.

Entry	Additive	Catalyst	Yield (%)	dr	eec (%)
1a	PhCO2Ha	13	52	4.9 : 1	87
2	PhCO2Hb	20	56	5.7 : 1	93
3	Et3Nb	20	13	4.9 : 1	n.d.
4	—	20	93	6.7 : 1	94
5	—	13	70	2.3 : 1	90
6	—	25	64	3.5 : 1	92
7	—	26	10	3.0 : 1	20
8	—	27	—	n.d.	n.d.

^a10 mol% loading of both catalyst and benzoic acid.

^b0.1 equiv. added.

^cMeasured for major diastereomer.