Palladium‐Catalyzed C—C Bond Activation/Suzuki Reaction of Methylenecyclobutanes

Abstract

Transition-metal catalyzed C-C bond activation is a formidable challenge owing to the high bond energy. We report here a novel palladium-catalyzed C-C bond activation manner of methylenecyclobutanes followed by subsequent Suzuki cross-coupling reaction affording multisubstituted indanes. The tandem reaction process involves intramolecular carbopalladation of double bond, β-carbon elimination and intermolecular trapping of the transient σ-alkylpalladium complex with boronic acids. A new TADDOL-derived phosphoramidite ligand bearing fluorine and silicon-based bulky groups is found to be efficient for C-C bond activation of methylenecyclobutanes.

Wacker Oxidation of Methylenecyclobutanes: Scope and Selectivity in an Unusual Setting

“…Any attempts to trap an intermediate arising from a β‐carbon elimination, such as running the reaction under a CO atmosphere, were unsuccessful. While this alludes to a concerted 1,2‐shift, it does not rule out a stepwise mechanism as suggested in Scheme 2 [19] …”

Palladium- and nickel-catalyzed cascade enantioselective ring-opening/coupling reactions of cyclobutanones

“…In addition, methylenecyclobutanes in which the oxygen of cycobutanones 3 was replaced with a methylene group were also amenable for the ring-opening/Suzuki–Miyaura cross-coupling reaction. 20…”

Wacker Oxidation von Methylencyclobutanen: Umfang und Selektivität in einer ungewöhnlichen Umgebung

“…B. die Durchführung der Reaktion unter einer CO‐Atmosphäre, waren erfolglos. Dies deutet zwar auf eine konzertierte 1,2‐Verschiebung hin, schließt aber einen schrittweisen Mechanismus wie in Schema 2 vorgeschlagen nicht aus [19] …”