Novel routes to bidentate cyclopentadienyl-alkoxy complexes of titanium

Man, Kwok Wai (1998) Novel routes to bidentate cyclopentadienyl-alkoxy complexes of titanium. University of Southampton, Doctoral Thesis.

Abstract

Reaction of C₅R¹₄ (SiMe₃)CHR²CH₂CR³CR⁴OR⁵ with titanium tetrachloride gives bidentate (η⁵, σ-C₅R¹₄CHR²CH₂CR³R⁴O) TiCl₂ through elimination of ClSiMe₃ and RCl (R = SiMe₃, CH₂Ph and CMe₃). A potentially tridentate system (R¹, R², R³ = H, R⁴ = -(CH₂)₂OMe) was synthesised in optically pure form. X-ray structure determination, and NMR studies confirmed that the pendant ether did not co-ordinate to the metal and the complex gave no enantioinduction in hydride transfer reactions. Efficient routes to tetramethylcyclopentadienyl substituted ligands (R¹ = Me) were developed through the addition of 2-magnesio-2-butene to γ-lactones followed by protection of the so formed pendant primary hydroxyl group and acid catalysed cyclisation. Indenyl and fluorenyl ligands carrying 3-hydroxypropyl substituents were synthesised, but did not form stable titanium complexes. The bidentate cyclopentadienyl-alkoxy titanium complexes were active catalysts for a variety of transformations.

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