V. V. Lipson

Molecular diversity of spirooxindoles. Synthesis and biological activity

Spirooxindoles are important synthetic targets possessing extended biological activity and drug discovery applications. This review focuses on the various strategies for the enantioselective synthesis of spirocyclic oxindoles relying on reports over the past decade and from earlier work. The spirooxindoles in this review are separated into three structural classes, and then further categorized into the method type from which the spirocycle is generated.

One hundred years of Meldrum’s acid: advances in the synthesis of pyridine and pyrimidine derivatives

A general review (138 references) focused on the recent advances in the application of Meldrum’s acid reactivity for synthesis of diverse pyridine and pyrimidine derivatives, mostly small and drug-like molecules is presented.

Synthesis of 9-Aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones

The reaction of 3-amino-1,2,4-triazole with arylidene derivatives of dimedone and their potential synthetic equivalents leading to the formation of 9-aryl-6,6-dimethyl-5,6,7,9-tetrahydro-1,2,4-triazolo[5,1-b]quinazolin-8(4H)ones has been studied. The direction of heterocyclization has been established, and the possible mechanisms for the formation of the pyrimidine heterocycle have been analysed.

Chemical Reactions of 2-Methyl-5,7-diphenyl-6,7-dihydropyrazolo[1,5-a]pyrimidine

The hydrolysis, oxidation, reduction, alkylation, formylation, and nitrosation reactions of 2-methyl-5,7-diphenyl-6,7-dihydropyrazolo[1,5-a]pyrimidine have been studied.

Cyclocondensation of 3-Amino-1,2,4-triazoles with Esters of Substituted Cinnamic Acids and Aromatic Unsaturated Ketones

We have studied the reactions of 3-amino, 3,5-diamino-, and 3-amino-5-trifluoromethyl-1,2,4-triazole with esters of substituted cinnamic acids and aromatic unsaturated ketones; we have established the directionality of formation of the tetrahydrooxopyrimidine ring. We have carried out hydrolysis and hydrazinolysis of 7-phenyl-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidin-5-one. We have conducted an X-ray diffraction study of isopropylidene hydrazide of 3-(5-amino-1,2,4-triazol-1-yl)-3-phenylpropionic acid.

Reactions of 4-oxobenz[1,3-e]oxazinium perchlorates with α-aminoazoles

Reactions of 4-oxo benz[1,3-e]oxazinium perchlorates with 1-R1-3-R2-5-aminopyrazoles lead to the formation of derivatives of pyrazolo[3,4-d]pyrimidine and pyrazolo[1,5-a]1,3,5]triazine series, and with 3-amino-1,2,4-triazole, to [1,2,4]triazolo[1,5-a][1,3,5]triazines.

Cyclocondensation of 3(5)-Aminopyrazoles with Arylglyoxals and Cyclohexane-1,3-diones

Partly hydrogenated 4-aroyl-substituted pyrazolo[3,4-b]quinolin-5-ones and 5-aroyl-substituted pyrazolo[1,5-a]quinazolin-6-ones were obtained by three-component cyclocondensation of substituted 3(5)-aminopyrazoles with the arylglyoxal hydrates and dimedone, 1,3-cyclohexanedione, or 4,4-dimethylcyclohexanedione in an alcohol medium. The chemical transformations of pyrazolo[3,4-b]quinolin5-ones in reactions with hydrazine hydrate and also upon alkylation, acylation, and oxidation were studied.

α,β-Unsaturated ketones based on allobetulone

Crotonization of allobetulone with aromatic and heteroaromatic aldehydes gave a number of new α,β-unsaturated ketones of the lupane series, and their steric structure was determined by X-ray analysis of (E)-4-[(3-oxoallobetulan-2-ylidene)methyl]benzonitrile as an example.

Synthesis of pyrrol-2-yl- and pyrazol-4-ylmethylidene derivatives of betulin and allobetulin

Aldol-crotonic condensation of allobetulone and betulonic aldehyde with N-substituted pyrrole-2- and pyrazole-4-carbaldehydes afforded a series of new α,β-unsaturated ketones of lupane series. Their reduction provided 2-ylidene derivatives of allobetulin and betulin, potential chiral components of liquid crystal materials. Structures of 1-phenyl-3-(4-phenoxyphenyl)-1H-pyrazole-4-carbaldehyde, (E)-2-{[3-(4-methoxyphenyl)-1-phenyl-1H-pyrazol-4-yl]methylidene}allobetulone, (E)-2-{[3-(4-bromophenyl)-1-phenyl-1H-pyrazol-4-yl]methylidene}-3-oxolup-20(29)-ene-28-carbaldehyde, (E)-2-{[3-(4-bromo-phenyl)-1-phenyl-1H-pyrazol-4-yl]methylidene}allobetulin, and (E)-2-{[3-(4-bromophe-nyl)-1-phenyl-1H-pyrazol-4-yl]-methylidene}lup-20(29)-ene-3,28-diol were established by X-ray diffraction (XRD) study.

THREE-COMPONENT SYNTHESIS OF 4-AROYL- 2(1),4,5,7-TETRAHYDROPYRAZOLO(3,4-b)PYRIDIN-6-ONES AND THEIR PROPERTIES

Inspired by the concept of multicomponent reactions, a novel one-pot synthesis involving arylglyoxals, 5-aminopyrazoles, and Meldrums acid has been developed and employed for the creation of a small library of 4-aroyl-2(1),4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-ones. The alkylation, acylation, reduction, and oxidation reactions of 4-aroyl-3-methyl-2,4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-ones have been studied.