posted on 2021-03-16, 16:14authored byYimin Jia, Yuan Yuan, Jinfeng Huang, Zhong-Xing Jiang, Zhigang Yang
With Ph3P+CF2COO– or TMSCF2Br as the difluorocarbene
sources, a facile
metal-free cycloaddition between heteroconjugated alkenes and difluorocarbene
was developed for the highly convergent synthesis of novel difluorinated
heterocyclics, including gem-difluorinated azetidines
and 2,3-dihydrobenzofurans. The cycloaddition features high reactivity
and regioselectivity, as well as good tolerance of various electron-donating
or electron-withdrawing substituents on azaheptafulvenes and o-quinone methides.