The reduction of pseudo-geminal bis(ethynyl)-substituted [2.2]paracyclophanes provides compounds with new bridges. The type of bridging is substituent dependent. The (trimethylsilyl)ethynyl moiety induces the formation of a bridge with two semicyclic double bonds; less bulky substituents, like propynyl and phenylethynyl, lead to bridges with endo double bonds.
Intramolecular Reactions in Pseudo-Geminally Substituted [2.2]Paracyclophanes
作者:Lidija Bondarenko、Silke Hentschel、Helmut Greiving、Jörg Grunenberg、Henning Hopf、Ina Dix、Peter G. Jones、Ludger Ernst
DOI:10.1002/chem.200601629
日期:2007.5.7
A selection of pseudo-geminally substituted [2.2]paracyclophanes, the alkynes 6, 7, 10, 11 a, and 11 b and the alkenes 8 and 9 were prepared for the study of intraannular reactions between functional groups in direct juxtaposition. Whereas 9 and 10 provide the corresponding cyclobutane and cyclobutene derivatives on irradiation (12 and 13, respectively), the bis-alkynes 7 and 11 b do not lead to a
Selenium halide-induced bridge formation in [2.2]paracyclophanes
作者:Laura G Sarbu、Henning Hopf、Peter G Jones、Lucian M Birsa
DOI:10.3762/bjoc.10.266
日期:——
An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene substructure. The reactions have been found to be sensitive to the substitution of the ethynyl group. The formation of dienes with a zig-zag configuration is related to that observed for non-conjugated cyclic diynes of medium ring size