Mechanistic study of Wittig-Horner type condensation for unsymmetrical TTF synthesis

The preparation of the DMBTTF 4 has been taken as a model to investigate the mechanism of the pseudo-Horner condensation, method generally used to selectively prepare unsymmetrically substituted TTF derivatives. The results obtained are described. They have allowed us to propose a mechanism of the reaction together with a one pot experimental procedure leading to 4 in a very high yield. This protocol have been then extended to the preparation of a various series of unsymmetrical TTF. In most of the cases the yield obtained have been found higher than those given in the literature.