Intramolekulare Cyclisierung von terminal disubstituierten α, ω-Diinen an Titanocen “Cp2Ti” mit einer nachfolgenden, ungewöhnlichen Cp-ringöffnung und neuen intramolekularen CC-Knüpfung
作者:A. Tillack、W. Baumann、A. Ohff、C. Lefeber、A. Spannenberg、R. Kempe、U. Rosenthal
DOI:10.1016/0022-328x(96)06307-3
日期:1996.8
The reaction of Cp(2)Ti(Me(3)SiC(2)SiMe(3)) (1) with terminal disubstituted alpha,omega-diynes RC=C-(CH2)(n)-C=CR affords, after substitution of Me(3)SiC(2)SiMe(3), bicyclic titanacyclopentadienes via intramolecular cyclization. The stability of the obtained products 2, 3 and 5 is determined by the spacer length (n = 2, 4, 5, 6). The four-membered ring derivatives (n = 2) 2a and 2b were obtained in good yield. In the case of n = 4 the bicyclic six-membered ring 3 was formed at first, which rearranges to a stable tricyclic eta(4): eta(3)-dihydroindenyl-Ti complex 4 by Cp cleavage and intramolecular C-C coupling. Complex 4 was characterized by X-ray structure analysis and NMR spectroscopy. An increase of spacer length (n > 4) provides indefinable secondary and decomposition products.