Reversal of chemoselectivity in Diels-Alder reaction with alpha,beta-unsaturated aldehydes and ketones catalyzed by Brønsted acid or Lewis acid.
[reaction: see text] High chemoselectivity was observed in the Diels-Alder reaction of alpha,beta-unsaturated aldehyde and alpha,beta-unsaturated ketone with cyclopentadiene. Using Tf2NH as catalyst, the reaction gave Diels-Alder adduct derived from alpha,beta-unsaturated ketone as a major product. On the other hand, bulky Lewis acid, B(C6F5)3, gave mainly the cycloadduct of alpha,beta-unsaturated aldehyde and cyclopentadiene.
Nakashima
Daisuke
D
Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA.
Yamamoto
Hisashi
H