3-Methyl derivatives of 1-substituted 3,4-dihydroisoquinoline were obtained proceeding from eugenol and its methyl ether. The propylene oxide in a three-component reaction with veratrol and ethyl cycnoacetate provided the reaction products in a low yield. The isoeugenol in a linear synthesis also gives a low yield of the target compounds.Quite a number of studies deals with the syntheses of 3-substituted 3,4-dihydroisoquinoline since the latter and the easily obtained therefrom 1,2,3,4-tetrahydro derivatives exhibit a wide range of the biological action. 1,3-Dimethyl-3,4-dihydroisoquinoline induces the Parkinson's syndrome [1], 7-substituted 1,3-dimethyl-1,2,3,4-tetrahydroisoquinolines are inhibitors of the phenylethanolamine-N-methyltransferase [2], 7-hydroxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is the inhibitor of NS3 protease of hepatitis C virus [3].The majority of the preparation methods of 3-methyl derivatives of 3,4-dihydroisoquinoline is underlain by the reaction of Bischler-Napieralski. N-(2-Chlorobenzoyl) amphetamide undergoes the cyclization into 3-methyl-1-(2-chlorophenyl)-3,4-dihydroisoquinoline at heating in the presence of POCl 3 in 37% yield [4], and 1-phenyl-3,4-dihydroisoquinoline forms in 13% yield [5]. A series of 1-hetaryl-substituted 3-methyl-3,4-dihydroisoquinolines was obtained by heating the eugenol methyl ether with hetarylamides or hetarylaldoximes in POCl 3 in 16-35% yields [6]. (S)-3-Methyl-3,4-dihydroisoquinoline was prepared from the corresponding N-phenethylformamide in polyphosphoric acid in 65% yield [7]. The application of Ritter reaction to the preparation of 3-methyl derivatives of this class compounds would extend the range of reqagents involved and make it possible to obtain compounds close in the structure to the naturally occurring substances. The use of the butyric aldehyde in the three-component synthesis of 3,4-dihydroisoquinoline derivatives resulted only in the preparation of the corresponding 9,10-diethylanthracene [8], whereas the eugenol methyl ether reacted with veratronitrile in sulfuric acid to give 1-arylsubstituted 3-methyl-6,7-dimethoxy-3,4-dihydroisoquinoline [9], but a plausible yield (53%) was obtained only with 3,4-dimethoxybenzonitrile whereas with the anisonitrile the yield of isoquinoline was only 15%, and with 3,4-diethoxybenzonitrile, less than 1%. The reaction of safrole with 3,4,5-trimethoxybenzonitrile in 48% HBF 4 gave the corresponding 3,4-dihydroisoquinoline in 17% yield whereas in the sulfuric acid only tar was obtained [10]. Inasmuch as the carbocation character arising in the protonation of both safrole and eugenol methyl ether should be the same at the use of the propylene oxide we used in the fi rst stage of the research two procedures: a, a three-component synthesis from veratrol, propylene oxide, and nitriles, and b, from the methyl ether of eugenol and nitriles.The reaction of veratrol, propylene oxide, and ethyl cycnoacetate brought simultaneously into concn. sulfuric acid led to the formation in a low yield of ethyl (2Z)-6...

The growing threat of proliferation of biofilm-forming hospital strains of coagulase-negative staphylococci resistant to antibiotics determines the need for an urgent search for new effective antibacterial compounds, as well as the development of methods for the combined use of traditional and alternative antibiotics. The article presents the results of a study of the combined effect of the drug «SA» — a new synthetic derivative of the alkaloid isoquinoline and a low-molecular-weight cationic peptide of the lantibiotic family hominin, which inhibits the development of bacterial biofilms of the clinical strain of Staphylococcus haemolyticus and its vancomycin-resistant isolates. It was found that combinations of these compounds have a synergistic effect that suppresses the formation of biofilms of both studied strains of staphylococci at reduced concentrations of these antibacterial compounds.

A new approach for the efficient and convenient synthesis of novel aminoalkyl-functionalized 4-arylquinolines via the Friedländer reaction of differently substituted 2-(3,4-dihydroisoquinolin-1-yl)anilines with various α-methylene ketones in acetic acid was developed. The reaction allows easy access to a diversity of 4-arylquinoline derivatives in moderate to excellent yields under mild conditions.

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