Dithienylethene Based Photochromic Siloles: a Straightforward and Divergent Synthetic Strategy.

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. The reaction is functional group-tolerant and can be performed in high yields with a variety of functional terminal alkynes. It can even be extended to a polymeric polypropargylmethacrylamide ( PPMA ) substrate affording the corresponding photochromic polymer with different degree of photochromic unit incorporation by simply adjusting the polymer / silirene stoichiometric ratio.