Mechanistic approaches to palladium-catalyzed alkene difunctionalization reactions

Abstract

Alkene difunctionalization, the addition of two functional groups across a double bond, exemplifies a class of reactions with significant synthetic potential. This emerging area examines recent developments of palladium-catalyzed difunctionalization reactions, with a focus on mechanistic strategies that allow for functionalization of a common palladium alkyl intermediate.

Fig. 1

Mechanistic possibilities for Pd-alkyl intermediates.

Fig. 2

Pd-catalyzed diamination of terminal dienes.

Fig. 3

Pd-catalyzed asymmetric diamination of dienes and alkenes.

Fig. 4

Pd-catalyzed difunctionalizations involving oxypalladation–alkene insertion.

Fig. 5

Pd-catalyzed difunctionalization reactions involving aminopalladation–alkene insertion.

Fig. 6

Pd-catalyzed dioxygenation of o-vinylphenols.

Fig. 7

Asymmetric dialkoxylation of o-vinyl phenols.

Fig. 8

Intramolecular Pd-catalyzed difunctionalization reactions.

Fig. 9

Mechanistic experiments supporting syn-aminopalladation and S_N2-type substitution.

Fig. 10

Pd-catalyzed aminoacetoxylation of alkenes and mechanistic experiments.

Fig. 11

Pd-catalyzed aminooxygenation of alkenes and mechanistic experiments.

Fig. 12

Pd-catalyzed cyclopropanation of enynes.

Fig. 13

Pd-catalyzed dioxygenation of alkenes.

Scheme 1

Proposed mechanism for Pd-catalyzed diene difunctionalization.

Scheme 2

Proposed mechanism for Pd-catalyzed diene difunctionalization reaction with diaziridinones.

Scheme 3

Proposed mechanism for Pd-catalyzed difunctionalization reactions involving nucleopalladation–alkene insertion.

Scheme 4

Proposed mechanism for Pd-catalyzed dihydroxylation or hydroxyalkoxylation of o-vinyl phenols.

Scheme 5

Proposed mechanism for Pd-catalyzed dialkoxylation of o-vinyl phenols.

Scheme 6

Proposed mechanism for Pd-catalyzed difunctionalization involving Pd^II–Pd^IV oxidation.