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

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

doi:10.1002/anie.202102882

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

Angew Chem Int Ed Engl. 2021 Sep 1;60(36):19598-19603. doi: 10.1002/anie.202102882. Epub 2021 Jun 4.

Authors

Kewei Sun¹, Keisuke Sagisaka¹, Lifen Peng^{2

3}, Hikaru Watanabe², Feng Xu², Rémy Pawlak⁴, Ernst Meyer⁴, Yasuhiro Okuda², Akihiro Orita², Shigeki Kawai^{1

5}

Affiliations

¹ Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki, 305-0047, Japan.
² Department of Applied Chemistry and Biotechnology, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama, 700-0005, Japan.
³ Key Laboratory of Theoretical Organic Chemistry and Functional Molecule of Ministry of Education, Hunan Provincial Key Laboratory of Controllable Preparation and Functional Application of Fine Polymers, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan, 411201, China.
⁴ Department of Physics, University of Basel, Klingelbergstrasse 82, 4056, Basel, Switzerland.
⁵ Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan.

PMID: 33955126
DOI: 10.1002/anie.202102882

Abstract

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 (-Me₂ Si-) through CH₃ -Si bond activation at 130 °C and subsequent elimination of the tethers at an elevated temperature of 200 °C.

Keywords: chemoselectivity; desilylative cross-coupling; on-surface oligomerization; para-phenylene ethynylenes; scanning probe microscopy.