Table 5.

Activation of oxazaborolidine 183 for Diels-Alder reaction with cyclopentadiene

entry	activator	mol%	dienophile	time	yield	ee	ref
1	MsOH	5%	Et acrylateb	1h	0%	--	78
2	TfOH	5%	Et acrylateb	1h	30%	97%	78
3	Tf2NH	5%	Et acrylateb	1h	43%	97%	78
4	186	5%	Et acrylateb	1h	73%	>99%	78
5	SnCl4	1%	methacroleinc	2h	>99%	95%	81
6	SnCl4	10%	Et acrylatec	16h	96%	95%	81
7	SnCl4	10%	di-Me-quinonec	1.5h	94%	99%	81

^aexperiments were conducted in DCM, [0.2M] in dienophile at −78 °C

^b5:1 diene to dienophile

^c3:1 diene:dienophile