I. P. Bezhan

Synthesis of isoxazolidine derivatives from N-substituted hydroxylamines and α,Β-unsaturated ketones

The reaction of methyl vinyl ketone with N-Phenyl-hydroxylamine leads to a tautomeric mixture of 5-hydroxy-2-phenyl-5-methylisoxazolidine and its linear form, while the reaction with benzohydroxamic acid leads to linear products of addition to the oxygen or nitrogen atoms, depending on the reaction conditions. The first representatives of 5-hydroxyisoxazolidines with the residue of an aliphatic carboxylic acid attached to the nitrogen atom were obtained by acylation of 5-hydroxy-3,3,5-trimethylisoxazolidine.

1,1-Dialkyl-2-acyl-3-hydroxypyrazolidinium and 2,2-dialkyl-5-hydroxyisoxazolidinium salts

Salts of 1,1-dimethyl-2-acylhydrazines and 1,1-dialkylhydroxylamines add quantitatively to the double bond of oxo compounds with an unsubstituted vinyl substituent. The structure of the products depends on the nature of the substituent at the carbonyl group.1H and13C NMR spectroscopy indicated that acrolein derivatives have the cyclic structure of 1,1-dialkyl-2-acyl-3-hydroxypyrazolidinium and 2,2-dialkyl-5-hydroxyisoxazolidinium salts, while derivatives of phenyl vinyl ketone and hydrazide salts are the corresponding linear, hydrazinium salts. Ring-chain tautomerism was found for several derivatives of methyl vinyl ketone in solution.

Synthesis of nitrogen heterocycles by (4+2)?-cycloaddition from nitrogen-containing heterodienes (?azadiene synthesis?) (review)

The review is devoted to the (4+2)π-cycloaddition with conjugated nitrogen-containing dienes. The participation in the synthesis of 1-azadienes, 2-azadienes (Schiff bases, oxazoles, and the acridizinium ion), 1,4-diazadienes (dehydroindigo, etc.), 2,3-diazadienes (tetrazines, 4H-pyrazoles, and triazines), α,β-unsaturated azo compounds, 5,6-dihydrotriazines, formazans, and azadienes containing more than one heteroatom in the conjugation chain is examined. The azadiene synthesis is a method for the preparation of pyridines, quinolines, pyridazines, oxazines, oxadiazines with different degrees of saturation, and several other heterocycles.

5-Substituted 2-benzyloxazolidines

The reaction of N-benzylhydroxylamine with α,Β-unsaturated carbonyl compounds provides a method of synthesis of 5-hydroxy-2-benzyloxazolidines, nucleophilic replacement of the hydroxyl group in which gives the corresponding 5-amino- and 5-hydrazinoisoxazolidines.

The simplest phenylnitrones and their conversion into isoxazolidine derivatives

Reactions of N-phenylhydroxylamine with the simplest alkanals leads initially to the formation of N-phenylnitrones, dimerization of which gives 5-substituted isoxazolidine. Taking the reactions of N-phenylnitrones, benzaldehyde, and acetone as an example, the possibility of a crossover reaction has been established.