Regiospecific Synthesis of Bicyclo- and Heterobicyclo-<i>g</i><i>em</i>-difluorocyclobutenes Using Functionalized Fluoroallenes and a Novel Mo-Catalyzed Intramolecular [2 + 2] Cycloaddition Reaction

Abstract

The first synthesis of functionalized gem-difluoroallenes 4 served as platform for an unprecedented molybdenum-catalyzed intramolecular allene-alkyne [2 + 2]-cycloaddition that produced 6, a hitherto unknown class of bicyclo- and heterobicyclo-CF2-containing cyclobutenes.