Novel Mg-organic reagents in organic synthesis. Cp2TiCl2 catalyzed intermolecular cyclomagnesiation of cyclic and acyclic 1,2-dienes using Grignard reagents

High-yield (> 80%) catalytic intermolecular cyclomagnesiation of cyclic and acyclic allenes with the aid of Grignard reagents has been realized in the presence of Cp2TiCl2. The synthesized unsaturated bi- and tricyclic organomagnesium compounds (OMC) have been successfully converted in situ into thiophenes, unsaturated ketones, cyclic and acyclic hydrocarbons with high regio- and stereoselectivity. (c) 2008 Elsevier Ltd. All rights reserved.