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Alkylation by polyprenols of o- and p-cresols in the presence of equimolar amounts of the corresponding aluminum cresolates occurred regioselectively to form o-alkyl products regardless of the ratio of starting reagents. Production of 2,6-dipolyprenyl-4-methylphenol was favored if an excess of polyprenols was used with aluminum p-cresolate. A significant amount of polyprenol polymerization products was obtained under the studied reaction conditions.

Series of arylidene- and arylhydroxymethyl derivatives of 1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-3-one and 2,3,4,10-tetrahydro-1H-pyrido[2,1-b]quinazolin-10-one were synthesized. Schiff bases were synthesized from amine derivatives. Hydroxymethylidene derivatives and arylaminomethylidene-1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-9-ones and -2,3,4,10-tetrahydro-1H-pyrido[2,1-b]quinazolin-10-ones were obtained. The antimicrobial activity of the synthesized compounds against S. aureus, E. coli, Bacillus cereus, Candida albicans, and Pseudomonas aeruginosa was studied. It was concluded that the search for bactericides in these series was promising.

Deoxyvasicine thione (III) and mackinazoline thione (6,7,8,9-tetrahydro-11H-pyrido[2,1-b]quinazoline-11-thione, IV) were synthesized and condensed with aromatic and heterocyclic aldehydes at the α-methylene [CH2-3 (III) or CH2-6 (IV)]. Either 3- and 6-arylidene derivatives (V – XIII) or 6-hydroxymethylaryl derivatives (XIV) were formed depending on the reaction conditions. Formylation of IV synthesized the 6-hydroxymethylidene derivative (XV). 6-Chloro-, -hydroseleno-, and -anilinomethylidenemackinazoline thiones (XVI – XIX) were also synthesized. The antimicrobial activity of the synthesized compounds against S. aureus, E. coli, Bacillus cereus, Candida albicans, and Pseudomonas aeruginosa was studied.

While growing 2-ethylbenzimidazole crystals from methanol, polymorph 1с is obtained. In polymorphs 1а-с, 2-ethylbenzimidazole molecules have a different arrangement in the packing and the position of the ethyl group relative to the benzimidazole plane. At the same time, the character (sequence) of intermolecular N–H…N bonds is maintained. In polymorph 1b with four independent molecules, there is an intermolecular Н bond between homonymous molecules. The study of the crystal structure of another benzimidazole derivative (2-(1-hydroxyethyl)benzimidazole (2)) reveals a new polymorph. The results of the comparative analysis of the crystal structures of two polymorphs 2а, 2b are presented.

Quantum chemical calculations of energies, electronic structures, and molecular geometries of 3,5,6-trimethylthieno[2,3-d]pyrimidin-4-one (1), tricyclic 2,3-tri-, 2,3-tetra-, and 2,3-pentamethylene-substituted 5,6-dimethylthieno[2,3-d]pyrimidin-4-ones (2—4), carboxylic acids 5—8 resulting from oxidation of compounds 1—4 at the methyl group in position 5 of thienopyrimidine, methyl esters of these acids (9—12), and products of ipso-nitration of esters (13—16) were performed in terms of the HF and DFT (B3LYP) approximations with the 3-21G basis set. Also, calculations for mixed anhydrides of nitric acid and carboxylic acids 17—20 were carried out. The possible causes of differences in the behaviors of 3-unsubstituted and 3-substituted thieno[2,3-d]pyrimidin-4-ones were discussed.

Results of the last 15–20 years on the isolation, synthesis, chemical modification, and biological activity of natural tricyclic quinazolines and their synthetic analogs were reviewed.

The quantum chemical calculations of the energies, electronic structures, and geometries for the products and intermediates of the ipso-nitration of 5,6-dimethyl-substituted 2-oxo- and 2-thioxothieno[2,3-d]pyrimidin-4-ones, as well as 6-methyl-5-nitrothieno[2,3-d]pyrimidin-4-one and 3,6-dimethyl-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidine-5-carboxylic acid formed under the action of a nitrating mixture on 5,6-dimethylthieno[2,3-d]pyrimidin-4-one and 3,5,6-trimethylthieno[2,3-d]pyrimidin-4-one, respectively, were performed in terms of the HF and DFT (B3LYP) approximations in the 3-21G basis set. Taking into account the substituent effects in the pyrimidine cycle, solvents, and prototropic tautomerism, possible reasons for the predominant ipso-substitution of the methyl group at the C(5) atom by the nitro group of the thienopyrimidine system and differences in behavior of 3-unsubstituted and 3-substituted thieno[2,3-d]pyrimidin-4-ones were considered.

Methods for preparing of 8-nitro- and 8-aminomackinazolinones were improved. 8-Acetyl(benzoyl)aminomackinazolinones reacted smoothly with aromatic aldehydes and furfurol in glacial acetic acid to give the corresponding 4-arylidene-substituted derivatives. Reaction of 8-aminomackinazolinone with aromatic aldehydes in glacial acetic acid was accompanied by acetylation of the amine and gave 8-acetylamino-4-arylidenemackinazolinones. Reaction of 8-aminomackinazolinone and p-nitrobenzaldehyde in propionic acid produced 8-[(4′ -nitrobenzylidene)amino]-4-(4″-nitrobenzylidene)mackinazolinone. In contrast, the reaction in Py occurred selectively at the amine to form the corresponding Schiff base 8-[(4′-nitrobenzylidene)amino]mackinazolinone.

The thioanalog of mackinazolinone (2,3,4,10-tetrahydro-1 H-pyrido2,1-bquinazolin-10-one) was synthesized for the first time by reacting it with P2S5. The thioanalog was reacted with aromatic aldehydes and Vilsmeier- Haack reagent (DMF + POCl3) to produce 4-arylidene- and -hydroxymethylidenemackinazolinthiones, respectively. The reactions of 4-hydroxymethylidenemackinazolinone with isomeric aminophenols and aminobenzoic acids and of hydroxymethylidenemackinazolinthione with thionylchloride were studied. Subsequent reaction of the obtained 4-chloromethylidene derivative with sodium hydroselenide was synthesized a new Se-containing derivative of mackinazolinone. It was shown that 4-formylmackinazolinthione existed in the enol form whereas 4-formylmackinazolinone existed as the enaminoaldehyde tautomer.

A new method for formylation of deoxyvasicinone (DOV) was developed. Nucleophilic substitution of α-hydroxy- and -dimethylaminomethylidene-DOV by isomeric aminophenols and benzoic acids to give α-arylaminomethylidene-DOV was studied.

2,3-Dimethyl- and 2,3-tri-, 2,3-tetra-, and 2,3-pentamethylene-substituted 8-arylidene-6,7-dihydro-pyrrolo[1,2-a]thieno[2,3-d]pyrimidin-4-ones were synthesized by the reaction of 2,3-dimethyl- and 2,3-tri-, 2,3-tetra-, and 2,3-pentamethylene-7,8-dihydropyrrolo[1,2-a]thieno[2,3-d]pyrimidin-4(6H)-ones with benzaldehyde, its 4-dimethylamino-, 3,4-dimethoxy-, and 3,4-methylenedioxy derivatives and also furfural in the presence of NaOH.

The Pd-catalyzed arylation of isoalantolactone by deoxyvasicinone and lappaconitine halides occurred with formation mainly of cross-coupling products with the (E)-configuration of the double bond. Another three compounds were isolated from the reaction of isoalantolactone with 6-bromodeoxyvasicinone. These were the lactone diarylation product, a compound with the (Z)-configuration of the double bond, and a product with a shift of the C(11,13) double bond and configuration inversion at C(8). The new compounds are interesting as potential biologically active agents.

6-Acetylamino- and -benzoylamino-9-arylidenedeoxyvasicinones were synthesized by reaction of 6-amino(3), -acetylamino- (4), and -benzoylamino- (5) -deoxyvasicinones (DOV) with aromatic aldehydes and furfurol in glacial acetic acid. It was shown that the amino group of 6-aminodeoxyvasicinone underwent acylation upon reaction with aldehydes to form 6-acetylamino-DOV, which reacted with aldehydes to form 9-arylidene derivatives. Carrying out this condensation in toluene, o-xylene, and ethanol produced a mixture of condensation products at the 6-amino- and -CH 2 -groups. It was found that condensati on of 3 with 4-nitrobenzaldehyde in pyridine formed exclusively the Schiff bases. Methods for preparing 6-nitrodeoxyvasicinone and for its reduction were improved.

α-Aryliden-6H(nitro)- and 6,8-dibromo-2,3-tetramethylen-3,4-dihydroquinazol-4-ones were synthesized by condensation of 6H(nitro)- and 6,8-dibromo-2,3-tetramethylen-3,4-dihydroquinazol-4-ones with aromatic aldehydes, furfurol, and of α-formyl-2,3-tetramethylen-3,4-dihydroquinazol-4-one with benzaldehyde and 4-nitrobenzaldehyde in glacial acetic acid.

9-Arylidene-6H(nitro)deoxyvasicinones were synthesized by reaction of 6H(nitro)deoxyvasicinones and aromatic aldehydes and furfurol in glacial acetic acid.

Results of the last 15–20 years on the isolation, synthesis, chemical modification, and biological activity of natural tricyclic quinazolines and their synthetic analogs were reviewed.

The deuterium exchange rate of the α-methylene of deoxyvasicinone (1) and mackinazolinone (2) and their seven- (3) and eight-membered (4) homologs was studied in neutral, acidic, and basic media. It was found that the exchange rate depended on the number of methylenes in the polymethylene ring and the medium. The deuterium exchange rate decreased in the order 2→1→3→4 and was slowest in media close to neutral. The results agreed with those for the reactions of 1–4 with bromine in acidic medium, condensation with substituted aromatic and heterocyclic aldehydes, and acylation by aromatic acid chlorides. Several trends in the reactivity of the tricyclic quinazolin-4-ones were discovered.

A method was developed to prepare α-methyl(benzyl)deoxyvasicinones by alkylation of α-hydroxy- methylidenedeoxyvasicinone. It has been shown that the reaction proceeds anomalously through a deformylation step.

α-Piperazinylmethylenedeoxyvasicinones have been synthesized by the interaction of α-hydroxymethylenedeoxyvasicinones with various N-substituted piperazines.