PENTACOORDINATED CHLOROSILANES WITH <i>C,O</i>-CHELATE LIGANDS DERIVED FROM <i>N</i>-METHYL-<i>N</i>'-ORGANOSULFONYLPROLINAMIDES

Abstract

The reaction of amides RSO₂-Pro-NHMe with ClCH₂SiMe₂Cl in the presence of (Me₃Si)₂NH gave pentacoordinated chlorosilanes RSO₂-Pro-N(Me)CH₂SiMe₂Cl with an organosulfonyl group (R = Me, Ph, 4-ClC₆H₄, 4-BrC₆H₄, 4-MeC₆H₄, and 4-O₂NC₆H₄) attached to the proline nitrogen atom. An alternative method for the preparation of these compounds comprises the cyclosilylmethylation of proline methylamide by dimethylchloromethylchlorosilane to give the previously unreported heterocyclic 2-sila-5-piperazinone system in the first step. The bicyclic silacyclane synthesized is 2-sila-5-piperazinone condensed with a proline residue. The action of sulfonyl chlorides RSO₂Cl leads to cleavage of the sila ring Si–N bond to give the desired chlorosilanes. The hydrolysis of these products, depending on the reaction conditions, gives either silyloxonium chlorides [RSO₂-Pro-N(Me)CH₂SiMe₂OH₂]Cl or disiloxanes [RSO₂-Pro-N(Me)CH₂SiMe₂]₂O. X-ray diffraction structural analysis showed that the silicon atom in the chlorides and silyloxonium chlorides is pentacoordinated due to an intramolecular O→Si bond and has distorted trigonal-bipyrimidal configuration. ²⁹Si NMR spectroscopy showed that the disiloxanes and bicyclic sila-5-piperazinone have a tetracoordinated silicon atom.

Authors: A. A. Nikolin, D. E. Arkhipov, A. G. Shipov, E. P. Kramarova, N. A. Koval'chuk, A. A. Korlyukov, V. V. Negrebetsky, Yu. I. Baukov, A. R. Bassindale, P. G. Taylor, A. Bowden, and S. Yu. Bylikin.

English translation in Chemistry of Heterocyclic Compounds, 2011, 47 (12), pp 1565-1583

http://link.springer.com/article/10.1007/s10593-012-0949-7