Synthesis of Novel Fluorinated Benzofurans and Dihydrobenzofurans

Abstract : Starting from easily accessible propargylic fluorides an intramolecular oxa-Michael addition affords, in good yields, new gem-difluorodihydrobenzofurans bearing an electrophilic double bond in position 2. On these intermediates nucleophilic additions and Diels-Alder reactions have been performed affording functionalized fluorinated dihydrobenzofurans. On the other hand, Pd-catalyzed defluorinations give the corresponding fluorine containing benzofurans.