Synthesis of tripod-shaped oligo(phenylene)s with multiple ethenyl groups at the bases for chemisorption on hydrogen-terminated silicon surfaces

This communication describes an efficient and convergent synthesis of monodisperse, nanometer-sized, and tripod-shaped oligo(phenylene)s with a triallylsilyl group at the base of each leg and a chlorophenyl group at the focal point of the tripod. These molecules were designed as model compounds for the study of chemisorption of rigid molecules containing multiple ethenyl groups on hydrogen-terminated silicon surfaces. The compounds were synthesized from p-chlorophenyl-tris(p-bromopenyl)silane via selective Pd-catalyzed Ishiyama-Miyaura reaction with bis(pinacolato)diboron, followed by Suzuki coupling with aryl dihalides to elongate the legs. The legs were then end-capped with triallylsilyl groups through Suzuki coupling with 4-triallyphenylboronic acid. (C) 2003 Elsevier Science Ltd. All rights reserved.