INDENYLSILANES AND FLUORENYLSILANES - SYNTHESIS AND THERMAL DIASTEREOMERIZATION

Indenyl- and fluorenylmagnesium bromides were found to be particularly effective for the synthesis of LxSiCl4-x (L = Ind, Flu) and for their dimethyl and dimethoxy derivatives. The substitution of Si on indene occurs exclusively at the 1-position. Two diastereomers, the (R,R/S,S)-racemic and (R,S)-meso structures, were obtained and separated for (Ind)2SiX2 (X = Cl, OCH3, CH3). Thermal diastereomerization of racemic to meso structures has been shown to occur by the dynamic NMR method, and thermodynamic parameters have been determined. A possible mechanism involving intramolecular 1,3-metallotropic shifts for the diastereomerization process is proposed.