A straightforward synthetic methodology for the preparation of photochromic siloles based on the dithienylethene motif is developed. It relies upon an efficient palladium-catalyzed annulation reaction of a 2,3-bis(3-thienyl)-silirene with terminal alkynes in mild conditions.
This synthetic strategy for the obtention of photochromic silole-embeded DTEs involves a palladium-catalyzed [3+2] annulation reaction of a silirene with terminal alkynes. Our study illustrates the versatility of this reaction that takes advantage of the abundant terminal alkynes pool and offers a good functional group tolerance including alcohol, amine or amide functions.
Starting from phenyl(polyacetylene) the corresponding photochromic phenyl(polysiloles) are easily obtained. Starting from organosoluble polypropargylmethacrylamide (PPMA) and by simply adjusting the polymer / silirene stoichiometric ratio, the strategy can be easily transposed to the preparation of custom silole-contaning photochromic polymers.
Today, we disclosed an efficient synthetic methodology for a straightforward access to DTE based photochromic siloles by using a dithienylsilirene as a pro-photochromic synthon as a proof of concept.
Marc Devillard*, Nour Nour Eddine, Marie Cordier and Gilles Alcaraz*
Angew. Chem. Int. Ed. 2021, doi.org/10.1002/anie.202102540.
Published March 24, 2021