Subscribe to RSS
DOI: 10.1055/s-2008-1032205
Stereoselective Syntheses of Spirane Bridged Semi-titanocenes
Publication History
Received
8 November 2007
Publication Date:
28 February 2008 (online)
Abstract
The synthesis of bidentate cyclopentadienyl-alkoxide ligands and their complexation to titanium are described. The focus has been on methodology for stereoselective synthesis of ansa half-sandwich titanocenes with rigid C2- and C3-bridges which are embedded in a spirane scaffold. Intermediate reactions involve tandem acylation-alkylation in the conversion of a carbonyl carbon into a quaternary carbon and rhodium(I)-effected spiroannulations. Titanocene formation involved reaction between the dilithiated ligand and titanium(III) chloride, and subsequent oxidation of the trivalent titanium with lead(II) chloride whereby the semi-metallocene was formed.
Key words
spirane scaffold - ansa semi-titanocenes - C2- and C3-spirane bridges - geminal acylation-allylation - rhodium(I)-catalyzed spiroannulation