posted on 2017-10-11, 00:00authored byJiaheng Li, Cong Xu, Na Wei, Mang Wang
DBU-catalyzed sequential intermolecular
and intramolecular nucleophilic
addition reactions between gem-difluoroolefins and o-hydroxy/mercapto benzaldehydes have been developed to
provide a [4 + 2] annulation strategy for facile synthesis of gem-difluorinated isoflavanol derivatives. The competitive
addition–elimination reaction of gem-difluoroolefins
with nucleophiles was avoided under mild conditions, affording 2,2-difluorinated
4-isoflavanols or 2,2-difluoriated 4-thioisoflavanols in good to excellent
yields.