Recent advances in arene transformation reactions via chromium complexes

Abstract

Sequential addition of reactive carbanions and carbon electrophiles to arene Cr(CO)3 complexes yield, after decomplexation, trans disubstituted cyclohexa-dienes. Alkylation of the initially formed anionic cyclohexadienyl complex takes place with high selectivity (RI RBr » RC1 (unreactive); R = allyl prim, alkyl sec. alkyl; RI RCOR’) and is followed by carbonylation and transfer to the six-membered ring. Useful nucleophiles in this reaction appear to be those that react irreversibly with the complexed arene. The question of kinetic vs. thermodynamic control of nucleophilic addition to arene Cr(CO)3 complexes is discussed, and examples of highly regioselective reactions leading to 3-substituted benzocyclobutenes and 4-substituted indanes are presented. © 1985 IUPAC