Head-to-Tail Oligomerization by Silylene-Tethered Sonogashira Coupling on Ag(111)

Sun, Kewei;  Sagisaka, Keisuke;  Peng, Lifen;  Watanabe, Hikaru;  Xu, Feng;  Pawlak, Remy;  Meyer, Ernst;  Okuda, Yasuhiro;  Orita, Akihiro;  Kawai, Shigeki

On-surface synthesis is a powerful method for the fabrication of π-conjugated nanomaterials. Herein, we demonstrate chemoselective Sonogashira coupling between (trimethylsilyl)ethynyl and chlorophenyl groups in silylethynyl- and chloro-substituted partially fluorinated phenylene ethynylenes (SiCPFPEs) on Ag(111). The desilylative Sonogashira coupling occurred with high chemoselectivity up to 75 %, while the competing Ullmann and desilylative Glaser homocoupling reactions were suppressed. A combination of bond-resolved scanning tunneling microscopy/atomic force microscopy (STM/AFM) and DFT calculations revealed that the oligomers were obtained by the formation of intermolecular silylene tethers (-Me2Si-) through CH3−Si bond activation at 130 °C and subsequent elimination of the tethers at an elevated temperature of 200 °C.

Angewandte Chemie International Edition

Wiley

60

36

19598

19603

10.1002/anie.202102882