Zenta Tetere

Synthesis and antioxidant activity of new analogs of Quin-C1

New derivatives of 4-oxo-1,2,3,4-tetrahydroquinazoline, analogs of Quin-C1, have been synthesized by the condensation of aroyl- and heteroaroylhydrazides of anthranilic acid with cinnamic, crotonic, and 4-hydroxy-3-methoxybenzoic aldehydes. The antioxidant activity of the obtained compounds has been determined.

Synthesis of N′-cyclohexenecarbonyl-substituted hydrazides of 2-aminobenzoic acids and preparation of 3-cyclohexenyl-amido-1,2-dihydroquinazolin-4-ones based on them

N′-Cyclohexenecarbonyl-substituted hydrazides of 2-aminobenzoic acids were obtained from the reaction of isatoic anhydride with monohydrazides of cyclohexenedicarboxylic acid. Reaction of the 2-aminobenzoic acid hydrazides with substituted benzaldehydes gave 3-cyclohexenylamido-1,2-dihydroquinazolin-4-ones.

Synthesis of novel lupane triterpenoid-indazolone hybrids with oxime ester linkage.

Graphical abstract Figure. No Caption available. HighlightsNovel lupane triterpenoid‐indazolone hybrids with oxime linkage are obtained.This is the first report on oxime esters derived from betulonic and betulinic acid at their C(28).X‐ray structure of the hybrid molecule is reported.Purification procedure for betulonic acid via its cyclohexylammonium salt is developed. Abstract An efficient protocol for the synthesis of novel lupane triterpenoid‐indazolone hybrids with oxime ester linkage has been developed from naturally accessible precursor betulin. For the first time a series of betulonic acid‐indazolone hybrids have been synthesized via an acylation of corresponding 6,7‐dihydro‐1H‐indazol‐4(5H)‐one oximes with betulonic acid chloride. Diastereoselective reduction of the obtained betulonic acid conjugates with NaBH4 resulted in a formation of betulinic acid‐indazolone hybrids in excellent yields. The configuration of the key compounds has been fully established by X‐ray and 2D NMR analysis.

1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-Methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles

Abstract1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles have been obtained from the reaction of monohydrazides of 2-R-methyl-4-cyclohexen-1,1-dicarboxylic acids and hydrazides of 2-R-4-methyl-4-cyclohexen-1-monocarboxylic acids with acetylacetone and dibenzoylmethane. The conditions for the formation of the pyrazoles depend on the nature of the substituents in the hydrazide starting materials and the structure of the 1,3-diketone used.

Structural characterization of cevimeline and its trans-impurity by single crystal XRD.

Cevimeline is muscarinic receptor agonist which increases secretion of exocrine glands. Cevimeline base is a liquid (m.p. 20-25 °C) at ambient conditions, therefore its pharmaceutical formulation as a solid hydrochloride hemihydrate has been developed. The synthesis of cevimeline yields its cis- and trans-isomers and only the cis-isomer is recognized as the API and used in the finished formulation. In this study structural and physicochemical investigations of hydrochloride hemihydrates of cis- and trans-cevimelines have been performed. Single crystal X-ray analyses of both cis- and trans-isomers of cevimeline are reported here for the first time. It was found that the cis-isomer, the API, has less dense crystal packing, lower melting point and higher solubility in comparison to the trans-isomer.

Synthesis of Novel 4-Aminotetrahydropyrrolo[1,2-a]quinazoline Derivatives

Decarboxylation of substituted monohydrazides of 6-arylcyclohex-3-ene-1,1-dicarboxylic acids proceeds stereospecifically and leads to 1,6-cis-disubstituted cyclohex-3-enes. Due to the presence of the anthranilic acid moiety these decarboxylated hydrazides undergo formation of pyrrolo[1,2-a]quina-zolines when treated with 2-oxoglutaric acid. The present paper describes the first example of chemoselective synthesis of amide-linked conjugates between the cyclohexene moiety and tetrahydro-pyrrolo[1,2-a]quinazolines.

Synthesis of Derivatives of 3,5-Dioxopyrazolidine

The reaction of monohydrazides of 2-R-4-methylcyclohex-4-ene-1,1-dicarboxylic acids with ethoxymethylenemalonic acid diethyl ester leads to N-(2,2-diethoxycarbonylethylenyl)hydrazides of 2-R-4-methylcyclohex-4-ene-1,1-dicarboxylic acids, which are acylated by the anhydrides of trifluoroacetic and acetic acids with the formation of derivatives of 3,5-dioxopyrazolidine and 5-oxopyrazoline respectively.

Synthesis of 3-{3-[(4-methylcyclohex-3-enyl-carbonyl)amino]-4-oxo-3,4-dihydroquinazolin-2-yl}propanoic acid anilides

With the aim of discovering potential diuretic agents amongst quinazoline anilides we have prepared anilides of 3-{3-[(4-methylcyclohex-3-enylcarbonyl)amino]-4-oxo-3,4-dihydroquinazolin-2-yl}propanoic acid. Optimal conditions for obtaining of the starting acid have been established, and anilides have been synthesized by the mixed anhydrides method.

Synthesis of 1-Acyl-5-amino-4-ethoxycarbonylpyrazoles from Monohydrazides of Cyclohexenedicarboxylic Acids and Ethyl Ethoxymethylenecyanoacetate

Heating monohydrazides of cyclohexenedicarboxylic acids with ethyl ethoxymethylenecyanoacetate at reflux gives the corresponding N-substituted hydrazides. This reaction carried out in pyridine gives 1-acyl-5-amino-4-ethoxycarbonylpyrazoles.

Synthesis of Derivatives of Pyrazolin-1H-3-ones from 2′-N-Substituted Monohydrazides of Cyclohexenedicarboxylic Acids

Abstract2-(6-Aryl-4-methylcyclohex-3-enecarbonyl)-4-ethoxycarbonylpyrazolin-1H-3-ones have been synthesized from 2′-N-(2,2-diethoxycarbonylvinyl)monohydrazides of 6-aryl-4-methylcyclohex-3-ene-1,1-dicarboxylic acids by boiling in DMF, pyridine, or toluene in the presence of potassium carbonate. Under analogous conditions, but without potassium carbonate, 2′-N-substituted hydrazides of cyclohexenecarboxylic acids are obtained.