Irisa Rāviņa

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 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.

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.