Synthesis of cyclophanes via an intermolecular Pd-catalyzed enyne-diyne cross-benzannulation approach.
Several novel types of cyclophanes were efficiently synthesized via an intermolecular palladium-catalyzed cross-benzannulation of cyclic enynes and diynes. These types of cyclophanes are not accessible through an intramolecular mode of the homo-benzannulation protocol, reported previously. Cyclic reactants (enynes and diynes) were readily prepared in reasonable yields from commercially available materials using known procedures. The fact that the cyclic Z-enyne 29, in contrast to its E-counterpart, underwent benzannulation to produce the cyclophane 28 brought additional support for the necessity of having an E-hydrogen atom at the terminal olefin moiety of nonactivated enynes, which was found previously in the benzannulation of the acyclic substrates.
Gevorgyan
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Department of Chemistry, University of Illinois at Chicago, 845 Taylor Street, Chicago, IL 60607-7061, USA. vlad@uic.edu
Tsuboya
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N
Yamamoto
Y
Y