Selective functionalization of allylic C-H bonds into other chemical bonds are among the most straightforward and attractive, yet challenging transformations. Herein, a transition-metal-free protocol for direct allylic C-H nitrogenation, oxygenation,...
In this study, a
facile and efficient method to synthesize monofluoroalkenes
by photoredox catalytic defluorinative alkylation of gem-difluoroalkenes with 4-alkyl-1,4-dihydropyridines under mild conditions
(room temperature) is described. This novel strategy is applicable
for a broad range of gem-difluoroalkene substrates
with good functional group tolerance and a variety of 4-alkyl-1,4-dihydropyridines
(including primary, secondary, and even tertiary alkyl radicals).
Moreover, it also allows the challenging radical coupling with glycosyl-based
4-alkyl-1,4-dihydropyridines (DHPs) to synthesize monofluoroalkenylated
saccharides.
β-Thiolated-α-arylated ketones are perversive in bioactive molecules and serve as potential bidentate ligands for catalysis. Herein, a straightforward protocol to access β-thiolated ketones from aldehydes, alkenes, and disulfides enabled by the combination of photocatalysis and N-heterocyclic carbene catalysis is reported. The sequential radical addition to alkenes and subsequent radical−radical coupling cascade process simultaneously forge C−S and C−C bonds. The mild conditions allow for radical relay coupling with a broad functional group tolerance.
An
efficient and mild Zn-mediated decarboxylative/defluorinative alkylation
of α-trifluoromethyl alkenes using N-hydroxyphthalimide
esters as radical precursors was developed. Several α-trifluoromethyl
alkenes were readily coupled to a wide range of primary, secondary,
and tertiary radicals, affording the desired gem-difluoroethylenes
in moderate to excellent yields. This reaction protocol was also successfully
applied to the construction of complex molecules such as the bioactive
natural dehydroabietic acid and glycosyl groups bearing the gem-difluoroethylene moiety.
Three-membered cyclic structures are widely existing in natural products and serve as enabling intermediates in organic synthesis. However, the efficient and straightforward access to such structures with diversity remains a formidable challenge. Herein, a general and practical protocol to aziridines and cyclopropanes synthesis using free XH 2 (X = C or N) with alkenes by thianthrenation is presented. This metal-free protocol features the direct aziridination and cyclopropanation with unprotected XH 2 . Free sulfonamides, amides, carbamates, amines, and methylene with acidic protons, are good precursors, providing an attractive alternative for straightforward synthesis of aziridines and cyclopropanes from easily available starting materials.
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