Catalysis by temporary covalent activation. A novel catalysis of unactivated Diels-Alder reactions
摘要:
Diels-Alder reactions of cis-2-chlorovinyltributylstannane are greatly accelerated by tbe presence of catalytic amounts of haloboranes. Mechanistic studies support a mechanism for the catalysis involving an intermediate boron-activated dienophile. A similar but simpler catalysis of Diels-Alder reactions of unactivated alkynes, via a hydroboration - Diels-Alder - dehydroboration mechanism, is also described. (C) 1997 Elsevier Science Ltd.