Microwave-Assisted Copper Catalysis of α-Difluorinated <i>gem</i>-Diol toward Difluoroalkyl Radical for Hydrodifluoroalkylation of <i>para</i>-Quinone Methides
gem-diols by single electron oxidation. Under microwave irradiation, a catalytic amount of oxidant Cu(OAc)2 succeeds in the formation of transient difluoroalkyl radicals in situ, for the first time. The reaction features a simple protocol, short reaction time, scalability, and high yield. The synthetic utility of this new methodology was also explored for the synthesis of difluoroalkylated spiro-cyclohexadienones
A visible light promoted C(sp3)–H difluoromethylation of tetrahydroisoquinolines that uses stable and easily prepared α,α-difluorinated gem-diol as the CF2 source is disclosed.
Divergent Reaction of Activated Pyridines with α,α-Difluorinated <i>gem</i>-Diols: Regioselective Synthesis of <i>gem</i>-Difluorinated Dihydropyridines and Dihydropyridones
The nucleophilic reactivity of α,α-difluorinated gem-diols toward activated pyridinium salts has been capitalized in a highly regioselective fashion, offering biologically relevant 1,4-dihydropyridines and 3,4-dihydro-2-pyridones adorned with the valuable gem-difluoromethylene motif. The protocol is scalable as well as high yielding and accommodates a broad range of substrates and functional groups
An amination reaction of in situ generated gem-difluoro-enolates has been explored with electrophilic nitrogen sources. While their exposure to azodicarboxylates smoothly produced fluorinated alpha-amino ketones, reaction with nitro-soarenes (nitroso aldol reaction) furnished alpha-ketoamides in very high yields (up to 94%). The reaction is very fast (typically completed within 5 min) and scalable and tolerates various sensitive functional groups. Synthetic utility of this process was highlighted through the production of diverse nitrogen heterocycles and an orexin receptor antagonist.