METAL-TEMPLATE ELECTROPHILIC SUBSTITUTION ON PHENOLS - SYNTHESIS AND CRYSTAL-STRUCTURE OF BROMOMAGNESIUM PHENOLATE AND ITS REACTIVE COMPLEXWITH PARA-ISOPROPYLBENZALDEHYDE

The crystal structures of the bromomagnesium phenolate 5 and its compl ex 7 with para-isopropylbenzaldehyde are reported; for the first time it has been possible to demonstrate that the reactive complex 7, respo nsible for the complete ortho-regioselective control in the alkylation of phenoxymagnesium bromides with aldehydes, is not obtained by simpl e replacement of the ethereal ligand but by expansion of the metal coo rdination sphere from 4 (usual tetrahedral configuration) to 5. We inf er from H-1 NMR studies that the magnesium coordination of complex 7 i n solution is analogous to that shown in the solid state, with a compl exed ethereal molecule.