Preparation of C(3)-symmetric homochiral syn-trisnorbornabenzenes through regioselective cyclotrimerization of enantiopure iodonorbornenes.
C(3)-symmetric homochiral (-)-syn-trisoxonorbornabenzene 1 possessing a rigid cup-shaped structure was synthesized through a novel regioselective cyclotrimerization of enantiopure iodonorbornenes catalyzed by palladium nanoclusters. The yield of the cyclotrimerization was dependent on the stability of the palladium clusters, which was ascertained from the appearance and TEM images of the reaction mixtures. The efficient preparation of (-)-syn-1 was established in short steps, including the newly developed cyclotrimerization reaction. The thus-prepared homochiral (-)-syn-1 can serve as a key intermediate for the synthesis of C(3)-symmetric homochiral cup-shaped molecules with a helical arrangement of substituents. Introduction of several types of substituents was well demonstrated through palladium-catalyzed coupling reactions with the corresponding phosphate and triflate of (-)-syn-1.
Reza
A F G Masud
AF
Department of Functional Molecular Science, School of Physical Science, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8787, Japan.
Higashibayashi
Shuhei
S
Sakurai
Hidehiro
H