85664-58-0Relevant academic research and scientific papers
Dual Role of Pyrrolidine and Cooperative Pyrrolidine/Pyrrolidinium Effect in Nitrone Formation
Morales, Sara,Guijarro, Fernando G.,Alonso, Inés,García Ruano, José Luis,Cid, M. Belén
, p. 84 - 91 (2016/01/12)
The formation of nitrones by direct condensation between equimolecular amounts of N-substituted hydroxylamine hydrochlorides and aromatic or aliphatic aldehydes is efficiently promoted by pyrrolidine in a matter of minutes under very mild conditions in almost quantitative yields after a simple filtration through a short pad of silica gel. According to theoretical, spectroscopic, and experimental studies, this success is due to the ability of pyrrolidine to liberate the hydrochloride of the hydroxylamine and catalyze the reaction via iminium activation ion. Moreover, a cooperative pyrrolidine/pyrrolidinium chloride effect facilitates several steps of the catalytic cycle through proton transfer without hampering the nucleophilicity of the hydroxylamine by protonation.
The Influence of Steric and Electronic Effects on the Stability of Aldonitrones and on their Conversion into Isoxazolidines
Aurich, Hans Guenter,Eidel, Joachim,Schmidt, Michael
, p. 18 - 35 (2007/10/02)
The nitrones 3Aa-Ai were isolated from the reaction of tert-butylhydroxylamine (1A) with aldehydes 2a-i. 1B-D react in an analogous manner. 3Aa-Ac convert slowly into the isoxazolidines 5Aa-Ac, whereas 3Ad-Ai do not.Phenylhydroxylamine (1F) reacts with 2a-d to yield 5Fa-Fd, likewise compounds 5Ea, Ed and the rearranged product 5Ub are formed from 1E.Reaction of 1F and 2f-h, however, yields the nitrones 3Ff-Fh. 3Ff exists in an equilibrium with a dimer of structure 6. - Compounds 5Aa-Ac were found to undergo cycloreversion to give the nitrones 3 in solution, whereas 5Fa-Fd as well as 5Ea, Ub, and Ed did not.There is a steady decrease in the tendency for cycloreversion in the order 5Ab > 5Bb > 5Cb, however, the degree of cycloreversion is also solvent-dependent.Acyclic compounds 7 were found to be intermediates in the conversion of 5Aa and Bb into the corresponding nitrones.Compound 9, formed from 1A and acrolein (8), does not decompose to yield its components 3Aa and 11.The influence of electronic and steric effects on the relative stability of the nitrones 3 and isoxazolidines 5 is discussed.
Preparation of Vicinal N-Alkylamino Alcohols via Acylation-Rearrangement of Nitrones Followed by Hydride Reduction
Coates, Robert M.,Cummins, Clark H.
, p. 1383 - 1389 (2007/10/02)
Acylation-rearrangement of N-tert-butyl and N-cyclohexyl nitrones of cyclohexanecarboxaldehyde (1), n-butyraldehyde, isobutyraldehyde, 3-cyclohexenecarboxaldehyde, and α-methylpropionaldehyde gave α-pivaloyloxy imines, which underwent reduction with lithi
α-Oxygenation of Aldehydes and Cyclic Ketones by Acylation-Rearrangement of Nitrones
Cummins, Clark H.,Coates, Robert M.
, p. 2070 - 2076 (2007/10/02)
The reaction of N-tert-butylnitrones (1a-e) of aldehydes and N-methylnitrones (2 and 3) of cyclic ketones with acid chlorides in the presence of triethylamine afforded α-acyloxy imines by rearrangement of N-vinyl-O-acylhydroxylamine intermediates.Hydrolysis of the α-acyloxy imines gave α-acyloxy aldehydes and ketones.The acylation-rearrangement reaction offers a new method for α-oxygenation of carbonyl compounds.
