Collect. Czech. Chem. Commun. 1996, 61, 1722-1728

Titanium-Catalyzed [4+2] and [6+2] Cycloadditions of 1,4-Bis(trimethylsilyl)buta-1,3-diyne

Jan-Willem F. Kaagmana, Marco Repa, Michal Horáčekb, Petr Sedmerac, Jiří Čejkab, Vojtech Vargab and Karel Machb

a Inorganic Chemistry Laboratory, J. H. van't Hoff Institute, University of Amsterdam, 1018 WV Amsterdam, The Netherlands
b J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic
c Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague 4, Czech Republic


The (C2H5)2AlCl/TiCl4 catalyst induces the [4+2] cycloaddition of butadiene or the [6+2] cycloaddition of 1,3,5-cycloheptatriene (CHT) to individual acetylenic moieties of 1,4-bis(trimethylsilyl)buta-1,3-diyne (BSD). Heating of the 2:1 butadiene adduct, bis(2-trimethylsilylcyclohexa-1,4-dien-1-yl), to 250 °C yields 2,2'-bis(trimethylsilyl)biphenyl. The 1:1 adduct of BSD with CHT, 7-trimethylsilyl-8-trimethylsilylethynylbicyclo[4.2.1]nona-2,4-diene, is obtained as virtually the only product if the initial molar ratio CHT : BD equal to 1.86 is used.

Keywords: Titanium catalyst; Cycloadditions; 1,4-Bis(trimethylsilyl)buta-1,3-diyne; 1,3-Butadiene; 1,3,5-Cycloheptatriene.