Quadruple Functionalization of a Tetraphenylethylene Aromatic Scaffold with Ynamides or Tetracyanobutadienes: Synthesis and Optical Properties
Clotilde Philippe, Maëva Coste, Yann Bretonnière, Loı̈c Lemiègre, Sébastien Ulrich, Yann Trolez
Abstract
Abstract Ynamides are useful and versatile building blocks in organic synthesis, from which 1,1,4,4‐tetracyanobutadienes (TCBD) can be prepared for application in molecular electronics. However, their insertion onto multi‐functional molecular scaffold remains a synthetic challenge. In this work, we report the two‐steps synthesis in good isolated yield (64 % overall, 89 % stepwise) of a tetraphenylethylene (TPE) bearing four ynamides, and its further one‐step conversion into the tetra‐TCBD derivative through a [2+2] cycloaddition‐retroelectrocyclization sequence. The concomitant formation of the four ynamides required a specific optimisation of the reaction conditions. Although a poor fluorescent emitter in solution, the tetra‐TCBD compound displayed near‐infrared luminescence in the solid state, which is an attractive optoelectronic feature when considering future applications in molecular electronic devices.