Synthesis of new fused penta- and hexacyclic polynitrogen systems from 1H-benzimidazol-2-ylacetonitrile

Synthesis and properties of new benzo[4,5]thiazolo[3,2-a]pyrimidine derivatives

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Heating a mixture of substituted malonic esters and 6-methoxy-1,3-benzothiazolyl-2-amine afforded new derivatives of benzo [4,5]thiazolo[3,2-a]pyrimidine, 3-substituted 2-hydroxy-4Н-benzo[4,5]thiazolo[3,2-a]pyrimidine-4-ones. The choice between the possible tautomers was carried out basing on the Xray diffraction analysis of 3-formyl-2-chloro derivative synthesized by formylation of unsubstituted heterocycle by Vilsmeier reaction.

The interest to the synthesis and investigation of derivatives of fused pyrimidines is due to the wide range of the biological activity exhibited by this class of heterocycles, including antitumor, antibacterial, antiviral, antiinflammation, neurotrophic, and other types of action [1,2].

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“…Heating a mixture of substituted malonic esters and 6-methoxy-1,3-benzothiazolyl-2-amine afforded new derivatives of benzo [4,5]thiazolo[3,2-a]pyrimidine, 3-substituted 2-hydroxy-4Н-benzo[4,5]thiazolo[3,2-a]pyrimidine-4-ones. The choice between the possible tautomers was carried out basing on the Xray diffraction analysis of 3-formyl-2-chloro derivative synthesized by formylation of unsubstituted heterocycle by Vilsmeier reaction.…”

“…In continuation of the studies on the synthesis and exploration of new polycyclic fused pyrimidines [3][4][5] we carried out a synthesis of new derivatives of a tricyclic heterocyclic system benzo [4,5]thiazolo [3,2-a]pyrimidine and tested their antibacterial properties and their ability to inhibit the monoamine oxidase (MАО). The appropriateness of the study of monoamine oxidase inhibition with compounds synthesized is based on the existing data on docking of MAO-B inhibitors that have been found in a number of potentially active derivatives of phenyl-substituted 1,3-thiazoles [6] having structural analogy to the obtained compounds.…”

“…By heating 6-methoxy-1,3-benzothiazol-2-amine 1 and malonic esters 2a-2g on Wood's metal bath we obtained substituted 4Н-benzo [4,5]thiazolo[3,2-а]pyrimidine-4-ones 3a-3g. Two among these products were methylated with MeI in aqueous NaOH with the formation of О-methylated derivatives 4a and 4b.…”

“…It should be mentioned that in the few existing reports on the synthesis of 2,4-(oxo, hydroxy)-substituted benzo- [4,5]thiazolo[3,2-a]pyrimidine [7][8][9] and its benzofused derivative, 9,11-(oxo, hydroxy)-naphtha-[1',2':4,5]thiazolo[3,2-а]pyrimidine [10] no proofs of the structure was published allowing a conclusion on the existence of a definite tautomer among А-C.…”