Synthesis of Cyclopropanes by Intramolecular Attack of N-Nucleophiles on the Central Carbon of (π-Allyl)palladium Complexes

Abstract

ortho‐Halobenzamides such as compound 1a react in the presence of allene and base with catalytic amounts of palladium(0) complexes to form cyclopropanes such as 3a. This reaction is believed to proceed via an intermediate palladacyclobutane and is the first example of a noncarbon nucleophile attack on the centre carbon of an (η3‐allyl)palladium complex leading, by reductive elimination, to cyclopropanes. The regiochemistry of the nucleophilic attack (central versus terminal carbon) depends on the nature of ligand and solvent as electron rich palladium complexes favour central carbon attack.

Tri-2-furylphosphine

“…93 Regioselective internal alkoxycarbonylation of terminal alkynes has also employed TFP as ligand, although superior results were obtained with a similar catalyst based on 2diphenylphosphinopyridine. 93 Regioselective internal alkoxycarbonylation of terminal alkynes has also employed TFP as ligand, although superior results were obtained with a similar catalyst based on 2diphenylphosphinopyridine.…”