m-CPBA Mediated Metal Free, Rapid Oxidation of Aliphatic Amines to Oximes

Abstract

An efficient, rapid oxidation of various aliphatic amines to oximes using m-CPBA as an oxidant in ethyl acetate is described. High conversion (100%) with >90% oxime selectivity is achieved at room temperature under catalyst-free conditions. Mild reaction conditions along with an easy work up procedure offer lower byproduct formation and high selectivity for oximes in good yield and purity.

Unexpected Products of Benzylamine Oxidation Catalyzed by Manganese Porphyrins: Some Factors that Play a Critical Role for Imine Formation

“…The control reaction, in the absence of any catalyst, afforded 36% OXI yield and low IMI and NIT yields (2% and 6%, respectively), but neither BZD nor AMD (Table , entry 15) were observed in this system. Patil e co‐workers studied the oxidation of aliphatic amines to oximes by m ‐CPBA in the absence of catalysts and also verified the formation of oximes as major products in these systems . In the presence of [Mn III TPPCl] catalyst, we observed an increase in the yields of IMI and OXI products to 7 and 72%, respectively (Table , entry 16), but, whereas [Mn III TPPCl] improved OXI formation reaction, product distribution did not differ significantly from that observed for the non‐catalyzed reaction (Table , entry 15).…”

“…OXI formation could be justified by the hydroxylation of benzylamine. Patil and co‐workers verified that m ‐CPBA in the absence of metal catalysts was able to hydroxylate several amines, generating a di‐hydroxylamine as an intermediate, in which the elimination of a water molecule resulted in the formation of OXI by the isomerization of a nitroso compound. In our PhIO/[Mn III TPPCl] system, however, we were unable to detect any intermediate, although high‐valence MnP active species long known to hydroxylate a variety of organic substrates …”

Novel chemoenzymatic oxidation of amines into oximes based on hydrolase-catalysed peracid formation

“…CAL-B mediated oxidation of benzylamine (1a) using ethyl acetate or lauric acid and the urea-hydrogen complex. Finally, we compared this methodology with the previously described using m-CPBA 16 in terms of environmental impact since both protocols are similar and allow synthesising the oximes in a simple manner. To achieve this, we performed a quantification of the E-factor 35 for both processes.…”

“…The corresponding nitriles, aldehydes and imines were observed in some cases as by-products, requiring a column chromatographic purification for the isolation of the oximes in 78-94% isolated yield. 16 Biocatalysis provides an efficient access to multiple classes of organic compounds. 17 Hydrolases and mainly lipases catalyse hydrolytic but also reverse reactions such as esterification, transesterification, aminolysis and ammonolysis, among others.…”

Dual Roles for Potassium Hydride in Haloarene Reduction: CSNAr and Single Electron Transfer Reduction via Organic Electron Donors Formed in Benzene

“…However, computational studies found these proposals to be untenable. 18,19 Our recent study critically examined the evidence presented for KOtBu as a single electron donor to haloarenes in a number of different reports and found that, in each case, organic additives initiate the BHAS reaction by forming organic electron donors in situ, 20 for example, electron donor 9 from phenanthroline 6 (Scheme 2A). 18 While organic additives are not absolutely required for most substrates in this transformation, 9,10,15 they significantly enhance the yield of the coupled products, simultaneously allowing reactions to be conducted at lower temperatures and for a shorter duration.…”