3-CHLORO-4-FLUOROTHIOPHENE-1,1-DIOXIDE - A NEW SYNTHETICALLY USEFUL FLUORODIENE

Simple, three step synthesis of a new fluorine containing diene, 3-chl oro-4-fluorothiophene-1,1-dioxide (4), from commercially available 3-s ulpholene (1) has been developed. The synthetic value of compound 4 as a Diels-Alder diene has been demonstrated by its reactions with vario us type of dienophiles: acetylenes, alkenes, furans, quinone and anthr acene. The reactions proceed with high regioselectivity to give good y ields of 3-fluoro-4-chloro substituted aromatics or cyclic chlorofluor odienes. In reactions with alkenes, immediate aromatisation often occu rs. In some instances, when reacted with a diene, compound 4 behaves a s a dienophile. (C) 1998 Elsevier Science S.A. All rights reserved.