Table 1.

Catalyzed Hetero-Diels–Alder of o-Quinone Methides^a

entry	catalyst	solvent	time (h)	yield (%)b	drc
1	MgCl2	CH2Cl2	1	<5	—
2	Pd(TFA)2	CH2Cl2	5	22	2:1
3	FeCl3·6H2O	CH2Cl2	6	36	6:1
4	FeCl3	CH2Cl2	1	57	4:1
5d	FeCl3, 4 Å MS	CH2Cl2	1	28	1:1
6	TMSCl/MeOH	CH2Cl2	1	26	4:1
7e	FeCl3	CHCl3	1.3	82	4:1

^aReaction conditions: diol (0.5 mmol, 1 equiv), p-methoxystyrene (2 equiv), catalyst (10 mol % with respect to diol) and 0.5 M with respect to diol, 0 °C to rt.

^bIsolated yields.

^cdiastereomeric ratio determined by ¹H NMR

^d4 Å MS (200 mg),

^eCHCl₃ stabilized with amylenes.