Double Friedel-Crafts acylation reactions on the same ring of a metallocene: synthesis of a 2,5-diacetylphospharuthenocene |
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Authors: | Carmichael Duncan Le Floch Pascal Le Goff Xavier F Piechaczyk Olivier Seeboth Nicolas |
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Affiliation: | Laboratoire Hétéroéléments et Coordination, Ecole Polytechnique, CNRS, 91128 Palaiseau cedex, France. duncan.carmichael@polytechnique.edu |
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Abstract: | The synthetic outcome of the Friedel-Crafts acylation of 1',2',3,3',4,4',5'-heptamethylphospharuthenocene reflects the nature of the acylating agent, with alkanoyl anhydride/trifluoromethanesulfonic acid (TfOH) reagents giving monosubstitution at the phospholyl ring, whereas alkanoyl chloride/AlCl(3) gives 2,5-disubstitution. DFT calculations indicate that this unusual double acylation can be facilitated by the intervention of the phosphorus atom at an early stage in the reaction trajectory, with the acyl group being delivered from the phosphorus atom into the ring 2- or 2,5-positions. |
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Keywords: | acylation density functional calculations metallocenes heterocycles sandwich complexes |
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