The
Sonogashira-type coupling of 2,2-difluoroethenyl tosylate with
a variety of aliphatic and aromatic terminal alkynes proceeds smoothly
even at room temperature to produce the corresponding difluorinated
enyne derivatives. 2,2-Difluoroethenyl tosylate is a useful difluoroethenyl
source because of its ready availability from 2,2,2-trifluoroethanol.
Some of the obtained enynes exhibit strong fluorescence in the solid
state. Further derivatization of a difluorinated enyne through Rh(III)-catalyzed
oxidative coupling has also been examined.