superacidic conditions, aniline and indolederivatives are sulfonylated at low temperature with easy-to-access arenesulfonic acids or arenesulfonyl hydrazides. By modification of the functional-group directing effect through protonation, this method allows nonclassical site functionalization by overcoming the innate regioselectivity of electrophilic aromatic substitution. This superacid-mediated sulfonylation
Through an original superelectrophile-promoted difluoroethylation in superacid, CF2-Me aromatic amines can be synthesized directly and regioselectivity. Applied to simple substrates, natural alkaloids and active pharmaceutical ingredients, this method offers an alternative for the late-stage synthesis of aryl methyl ethers bioisosters.
Upon activation under superacid conditions, functionalized tailor‐made N‐SCF3 sulfenamides served as reagents for the trifluoromethylthiolation of aromaticamines. This method has a broad substrate scope and can be used for the late‐stage functionalization of complex molecules such as alkaloids or steroids. Mechanistic studies based on in situ low‐temperature NMR spectroscopy revealed the involvement
Regioselective oxidation of indoles to 2-oxindoles
作者:Santosh V. Shelar、Narshinha P. Argade
DOI:10.1039/c9ob00764d
日期:——
Facile regioselective oxidation of indoles to 2-oxindoles promoted by sulfuric acid adsorbed on silica gel is reported. The demonstrated practical site-selective heterogeneous oxidation reactions conveniently take place with a broad substrate scope and functional group tolerances. The present oxidation strategy is also employed to accomplish the total synthesis of natural products donaxaridine and
to observe this ionic species, its extended lifetime in superacid solutions allowed its characterization by NMR‐based structural analysis supported by DFT calculations. This allyloxycarbenium ion was further exploited in the Ferrier rearrangement to afford unsaturated nitrogen‐containing C‐aryl glycosides and C‐alkyl glycosides under superacid and flow conditions, respectively.