Tris(benzocyclobutadieno)triphenylene and its lower biphenylene homologues by palladium-catalyzed cyclizations of 2,3-didehydrobiphenylene.
[reaction: see text] The Pd-catalyzed cycloaddition of didehydrobiphenylenes 2a,b, generated from the corresponding 3-(trimethylsilyl)-2-biphenylenyl triflates with fluoride, furnishes the C3-symmetric trimers 1a,b in which the embedded triphenylene unit is distorted to increase the aromaticity of the central benzene ring. Cocyclization of 2a,b with dimethyl acetylenedicarboxylate provides the phenanthrene- and naphthalenecarboxylic ester analogues, depending on the catalyst used.
Iglesias
Beatriz
B
Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Cobas
Agustín
A
Pérez
Dolores
D
Guitián
Enrique
E
Vollhardt
K Peter C
KP