Synthesis of 2-Cyclopentenone Derivatives via Palladium-Catalyzed Intramolecular Carbonyl α-Alkenylation

Abstract

2-Cyclopentenone derivatives have been efficiently synthesized from 5-bromo-5-hexen-2-ones via palladium-catalyzed intramolecular carbonyl α-alkenylation followed by double-bond migration under mild reaction conditions.

Methylenecyclopropane Ring Formation/Opening Cascade for the Synthesis of Indolizines

“…Previously, we developed a novel strategy toward the synthesis of furan-3-carboxylates from 3-substituted 2-(2′-bromoallyl)-3-oxo-1-carboxylate (Scheme ). The reaction went through an allenic intermediate and methylenecyclopropane ring formation/opening sequence. We further envisioned that substrates bearing a pyridinyl functionality, in place of the carbonyl group, could be used to achieve similar transformation to access indolizines by utilizing the nucleophilic character of the nitrogen atom.…”

A Palladium-Catalyzed Monodearoylative Dimerization Approach for the Synthesis of [3]Dendralenes

“…Previously, we developed a palladium-catalyzed intramolecular carbonyl α-alkenylation approach with 3-alkyl-2-(2-bromoallyl)-1,3-dicarbonyl compounds for the synthesis of 2-cyclopentenones . We further envisioned that treatment of the 3-aryl analogues might give rise to the formation of dihydro­naph­thalenones via aryl C–H activation.…”

“…Our investigation commenced with methyl 2-benzoyl-4-bromo-2-methylpent-4-enoate 1a . No reaction occurred after exposing 1a to Pd­(PPh 3 ) 4 and K 3 PO 4 in DMF for 8 h (entry 1, Table ). Pd/C also did not give any promising result (entry 2).…”