Palladium-catalyzed intramolecular α-arylation of aliphatic ketone, formyl, and nitro groups

Intramolecular arylation of properly designed substrates bearing a ketone, formyl, or nitro terminating group was achieved by use of a PdCl2(Ph3P)(2)-Cs2CO3 reaction system to form a variety of carbocyclic compounds. Arylation in ketone compounds afforded benzene-annulated bridged or spirocycloalkanone derivatives, depending on the structure of the cyclization precursors. Arylation in formyl compounds occurred at the alpha-position (alpha-arylation) or at the carbonyl carbon (carbonyl-arylation) depending on the structure of the cyclization precursors and on the reaction solvent. An alpha-arylated secondary nitro group was partially transformed to ketone in the manner of the Nef reaction, whereas a tertiary nitro group was partially eliminated to afford a styrene-type olefin. (C) 2004 Elsevier Ltd. All rights reserved.