Basic enemies of photochromism: irreversible transformation of fluorinated diarylethenes to polyenic enamines and enols

Non-photochemical degradation of perfluorinated photochromic diarylethenes (DAE) under Knoevenagel, Sonogashira or Wittig conditions was discovered. This base promoted formation of strongly colored non-photochromic byproducts has an impact in the field of molecular electronics due to the basic conditions often employed during deacylation and desilylation of the protected thiol anchoring groups of functionalized DAE. The products were identified as seven-membered ring systems of the bicyclo[5.3.0]deca-1,7-diene type. Their formation was rationalized by a tentative two-step reaction mechanism.