A method for siladifluoromethylation
of dialkyl phosphonates and
secondary phosphine oxides with TMSCF3 to produce nucleophilic
PV–CF2– transfer reagents is disclosed,
with multigram scale reactions included. Condition-dependent divergent
reactivity under the established conditions is demonstrated by the
formation of trifluoromethylphosphines. Both one-pot transformations
are operationally simple and employ inexpensive materials. Mechanistic
investigations suggest the divergent reactivity originates from a
common intermediate, with Li+ concentration directing the
chemoselectivity.
An
operationally simple protocol for direct N-
and O-difluoromethylation of 2-pyridones, quinolinones,
and isoquinolinones using commercially available TMSCF2Br is disclosed. The chemoselectivity is modulated by simple variations
in temperature, solvent, and strength of the base. Diverse, synthetically
relevant functional groups are tolerated, including functional groups
that have reported reactivity with TMSCF2Br. Gram-scale
reactions to prepare both N- and O-difluoromethyl compounds are included.
A method for the O-difluoromethylation of carboxylic acids using commercially available TMSCF 2 Br is disclosed. The devised benchtop reaction system is air-stable and offers mild reaction conditions while using readily available reagents and solvents. The method is applicable to both aliphatic and aromatic carboxylic acids while demonstrating compatibility with a range of commonly encountered functional groups. The difluoromethyl esters of FDA approved drugs and pharmaceutically relevant molecules are also presented, demonstrating the potential for late-stage functionalization.
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