Secondary amines dimethyldioxirane

The most widely employed methods for the synthesis of nitrones are the condensation of carbonyl compounds with A-hydroxylamines5 and the oxidation of A+V-di substituted hydroxylamines.5 9 Practical and reliable methods for the oxidation of more easily available secondary amines have become available only recently.10 11 12 13. These include reactions with stoichiometric oxidants not readily available, such as dimethyldioxirane10 or A-phenylsulfonyl-C-phenyloxaziridine,11 and oxidations with hydrogen peroxide catalyzed by Na2W044 12 or Se02.13 All these methods suffer from limitations in scope and substrate tolerance. For example, oxidations with dimethyldioxirane seem to be limited to arylmethanamines and the above mentioned catalytic oxidations have been reported (and we have experienced as well) to give... 

Secondary amines (R2NH) are oxidized to hydroxylamines (R2NHOH), which are resistant to further oxidation, by dimethyldioxirane and by benzoyl peroxide and NajHPOa. " ... 

Tertiary amine oxides can be converted into TV-hydroxy secondary amines provided that one of the TV-substituents can be selectively eliminated. This procedure has been applied to the synthesis of secondary A-hydroxy-a-amino acids 34 from the corresponding secondary a-amino acids using the /V-cyanoethyl group for transient protection of the secondary amine (Scheme 10) J40l More recently, direct oxidation with 2,2-dimethyldioxirane of a primary amine has been described for H-L-Val-OMe (82% yield) and H-L-Phe-OMe (54% yield))13 The reaction proceeds smoothly without epimerization, but no experimental details have been reported. 

Oxidation. Benzylic secondary amines are oxidized in high yield by dimethyldioxirane to nitrones,1 probably via hydroxylamines.2... 

Nitroxides,5 Cyclic secondary amines are oxidized by dimethyldioxirane (1) to nitroxides in yields >95%. 

Oxidation of secondary amines, such as piperidine (94), with dimethyldioxirane (95) led to synthesis of cyclic hydroxamic acids (Scheme 52) (93ACS(47)1141). 

Polymer-supported permthenate has also been used in two convergent pathways for the synthesis of isoxazoUdines with each route employing different starting materials in order to create the maximum structural diversity [73]. In the first route secondary hydroxylamines, readily prepared from amines by in situ treatment with dimethyldioxirane, were oxidized directly to nitrones using polymer-supported permthenate (PSP). Alternatively, primary alcohols were used as the... 

Primary, secondary and tertiary aliphatic amines are efficiently converted to nitro compounds in 80-90 % yield with dimethyldioxirane, a reagent prepared from the reaction of oxone (2KHSO5-KHSO4-K2SO4) with buffered acetone. Dimethyldioxirane (DMDO) has been used for the synthesis of 1,3,5,7-tetranitroadamantane (71) from the corresponding tetraamine as the tetrahydrochloride salt (70) and is an improvement over the initial synthesis using permanganate anion (Table 1.7). ° Oxone is able to directly convert some aromatic amines into nitro compounds. 

Tertiary alkyl primary amines can be oxidized to nitro compounds in excellent yields with KMn04.39S This type of nitro compound is not easily prepared in other ways. All classes of primary amine (including primary, secondary, and tertiary alkyl as well as aryl) are oxidized to nitro compounds in high yields with dimethyldioxirane.399 Other reagents that oxidize various types of primary amines to nitro compounds are dry ozone,4,111 various peracids,401 including peracetic and peroxytrifluoroacetic acids, f-butyl hydroperoxide in the presence of certain molybdenum and vanadium compounds,402 F7-H20-MeCN,41123 and sodium perborate.403... 

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