Basic enemies of photochromism: irreversible transformation of fluorinated diarylethenes to polyenic enamines and enols
A 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 impact in the field of molecular electronics due to basic conditions often employed during deacylation and desilylation of protected thiol anchoring groups of functionalized DAE. Products were identified as seven-membered ring systems of the bicyclo[5.3.0]deca-1,7-diene type. Their formation is rationalized by a tentative two-step reaction mechanism.