Oxidation of Primary Aliphatic and Aromatic Aldehydes with Difluoro(aryl)-λ3-bromane
摘要:
Oxidation of primary aliphatic aldehydes with p-trifluoromethylphenyl(difluoro)-lambda(3)-bromane in dichloromethane at 0 degrees C afforded acid fluorides selectively In good yields, while that of aromatic aldehydes In chloroform at room temperature produced aryl difluoromethyl ethers. A larger migratory aptitude of aryl groups compared to primary alkyl groups during a 1,2-shift from carbon to an electron-deficient oxygen atom in bromane(III) Criegee-type intermediates will result in these differences in the reaction courses.
Hypervalent λ<sup>3</sup>-Bromane Strategy for Baeyer−Villiger Oxidation: Selective Transformation of Primary Aliphatic and Aromatic Aldehydes to Formates, Which is Missing in the Classical Baeyer−Villiger Oxidation
undergoes BV rearrangement and produces an ester via facile reductive elimination of an aryl-lambda(3)-bromanyl group, because of the hypernucleofugality. The novel strategy makes it possible to induce selectively the BV rearrangement of straight chain primary aliphatic as well as aromatic aldehydes, which is missing in the classical BVO: for instance, octanal and benzaldehyde afforded rearranged formate
Exposure of sulfides and sulfoxides to trifluoromethanesulfonylimino(aryl)‐λ3‐bromane in dichloromethane at 0 °C results in a facile transfer of the sulfonylimino group to sulfur atoms and affords N‐triflylsulfilimines and ‐sulfoximines in high yields under transition‐metal‐free conditions. Imination of (R)‐methyl p‐tolyl sulfoxide proceeded with predominant retention of configuration at the stereogenic
to afford triflyl-substituted amines in moderate to high yields. Marked selectivity for tertiary over secondary C–H bonds was observed; primary (methyl) C–H bonds were inert. Addition of hexafluoroisopropanol to inhibit decomposition of 1 dramatically improved the C–H amination efficiencies. Second-order kinetics, activation parameters (negative activation entropy), deuterium isotope effects, and theoretical
We present the first synthesis of air/moisture-stable λ3-bromanes (9 and 10) by using a cyclic 1,2-benzbromoxol-3-one (BBX) strategy. X-ray crystallography and NMR and IR spectroscopy of N-triflylimino-λ3-bromane (12) revealed that the bromine(III) center is effectively stabilized by intramolecular R–Br–O hypervalent bonding. This strategy enables the synthesis of a variety of air-, moisture-, and
A simple method for direct metal-free C–H amination of unactivated hydrocarbons using easy-handling diacetoxy-λ3-bromane and triflylamide or sulfamate esters was developed.