Amines, tertiary reactions with oxygen

NL Benoiton, FMF Chen. Unexpected dimerization in the reactions of activated Boc-amino acids with oxygen nucleophiles in the absence of tertiary amine, in JE Rivier, GR Marshall, eds. Peptides, Structure and Function. Proceedings of the 11th American Peptide Symposium, Escom, Leiden, 1990, pp 889-891. 

The reaction of tertiary formamides with sulfur tetrafluoride in the presence of potassium fluoride leads to replacement of both the carbonyl oxygen and formyl hydrogen atoms by fluorine. The formyl group is directly converted into the trifluoromethyl group to give N-(trifluoromethyl)amines which are isolated in almost quantitative yield (see Section 8.2.10.). Thus, dimethylformamide, diethylformamide, piperidinc-l-carbaldehyde, morpholine-1-carbaldehyde and ethyl(phenyl)formamide were converted into the corresponding A -(tri-fluoromethyl)amines 11.175... 

Reactions with electrophilic substrates. Oxygen peroxide formed during the development of the early products and hydroperoxides can attack electrophilic substrates according to an ionic, nonradical reaction. In this way, carbon-carbon double bonds can be transformed into epoxides and tertiary amines into N-oxides. These are cooxidations with an ionic mechanism. 

Tertiary amines react with oxygen in the presence of platinum to give antides showing a strong preference for reaction at methyl groups. For example, oxidation of trimethylamine gives )V,iV-dimethyl-formamide in 74% yield, and /V-methylcyclohexylamine yields )V-formylcyclohexylairune in quantitative yield. 

Oxiranes may also be prepared by the cooxidation of aldehydes and olefins. There are two assumptions as regards the mechanism the oxidation occurs via either an acylperoxy radical or a peracid. The peracid oxidation is stereospecific. Experiments carried out with a view to assessing the radical versus nonradical mechanism indicate that the extent of the radical epoxidation depends on the structure of the olefin and the olefin/aldehyde ratio. Cooxidation in the presence of oxygen was achieved by irradiating the aldehyde and carrying out the reaction with the alkene after a suitable quantity of peracid had been obtained. Enantioselective epoxidation has been described in the reaction of (1-phenyl-alkylidene)malonitriles 63 catalyzed by optically active tertiary amines. ... 

Tert-Amines - sec-amines.1 When a tertiary amine in pyridine is shaken with 2-nitropropane and CuCl under oxygen, it is converted into a nitrosamine (5), which can be isolated in yields of 15-65% and then reduced to a secondary amine. The reaction proceeds through oxidation to an amine oxide (2) with conversion of (1) into 2-nitro-2-propanol (3). This decomposes into acetone and nitrous acid. The nitrous acid traps the secondary amine formed from the amine oxide (2) after rearrangement to the carbinolamine (4). It is noteworthy that even... 

Since amine oxides react with alkyl halides to give O-alkyl compounds which are cleaved by alkali to the tertiary amine and an aldehyde, this reaction also can be used to eliminate the oxygen from JV-oxides.163... 

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