E. A. Sorokina

Synthesis of 6-aryl-Substituted Azocino-[5,4-b]indoles from 1-aryl-Substituted 2-Ethyltetrahydro-β-Carbolines

We optimized the reaction of tetrahydropyridine ring expansion in 1-aryl-substituted tetrahydro-β-carbolines by the action of activated alkynes and achieved higher than 70% yields of the target indoloazocines. The substituents in the 1-aryl ring and at the indole nitrogen atom were shown to affect the rate and selectivity of this transformation.

Transformations of tetrahydro-1,4-benzoxazepines and tetrahydro-1,4-benzothiazepines under the action of alkynes. First example of the synthesis of tetrahydro-1,4-benzothiazonine-6-carboxylate

It was shown that 2,3,4,5-tetrahydro-1,4-benzoxazepines were cleaved at the N–C(5) bond under the action of activated alkynes in methanol, forming o-(methoxyethyl)- and o-(methoxybenzyl)-phenyl(aminoethyl) ethers. The cleavage rate depended on the electronic effects of the substituents at the C-5 atom. Thiazepine ring expansion in tetrahydro-1,4-benzothiazepine was achieved for the first time via reaction with methyl propiolate to give a benzothiazonine.

Transformations of 4,5,6,7-tetrahydrothieno[3,2-c]-and 1,2,3,4-tetrahydrobenzothieno[2,3-c]pyridines in reactions with alkynes activated by electron-withdrawing substituents

The transformations of tetrahydrothieno[3,2-c]-and tetrahydrobenzothieno[2,3-c]pyridines in the reactions with acetylenedicarboxylic ester, alkyl propiolates, and acetylacetylene in alcohols were studied. Tetrahydrobenzothieno[3,2-d]azocines and 2-methoxyethyl-3-vinyl-aminoethylbenzothiophenes were synthesized.

Transformations of cotarnine chloride by the action of silver acetylides and alkynes

Three-component reactions of cotarnine chloride with silver acetylides and methyl propiolate or ethynyl methyl ketone in acetonitrile, as well as two-component reactions of 5-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5-g]isoquinoline with alkynes in various solvents were studied. Performing them in 2,2,2-trifluoroethanol as the solvent, 10-phenylethynyl-substituted tetrahydro[1,3]dioxolo[4,5-i]-[3]benzazocines were obtained in good yields.

3-Methyl-1,2,3,4,5,6,1',2',3',4'-deca-hydro-spiro-[benz[f]isoquinoline-1,2'-naphthalen]-1'-one.

The title compound, C23H23NO, is the product of a tandem transformation of the double Mannich base bis(1-oxo-1,2,3,4-tertrahydro-2-naphthoylmethyl)amine hydrochloride in HBr solution upon heating. The tetrahydropyridine ring has a non-symmetrical half-chair conformation, whereas the cyclohexadiene and cyclohexene rings adopt non-symmetrical half-boat conformations. The dihedral angle between the planes of the terminal benzene rings is 62.85 (6)°. The N atom has a trigonal–pyramidal geometry [sum of the bond angles = 332.4 (3)°]. In the crystal, molecules form [001] chains via weak non-classical C—H⋯N hydrogen bonds. The chains are stacked along the b axis.

Synthesis of furyl-, furylvinyl-, thienyl-, pyrrolinylquinazolines and isoindolo[2,1-a]quinazolines

A method for the synthesis of hydrogenated furyl-, furylvinyl-, thienyl-, and pyrrolinyl-substituted quinazolin-4-ones was developed. A possibility of the reaction of 2-furylquinazolines with maleic anhydride was demonstrated. A number of quinazolines obtained were subjected to a primary bioscreening on inhibition of acetylcholinesterase.

Synthesis of Epoxyisoindolo[1,2-a]isoquinolinium Salts by an Intramolecular [2+4] Cycloaddition Reaction in 2-Allyl-1-furylisoquinolinium Halides

We examined the tandem alkylation/[2+4] cycloaddition of 1-(2-furyl)-3,4-dihydroisoquinolines by various allyl halides. It was found that the process occurred through the intermediate formation of 2-allyl-1-furyl-3,4-dihydroisoquinolinium salts with a subsequent intramolecular exo addition of the allyl fragment to the furan ring. The adducts obtained were structural analogs of the isoindolo-[1,2-a]isoquinoline alkaloids jamtine and hirsutine.

Synthesis of 4-amino-substituted tetrahydropyrimido[4,5-d]azocines

A method for the preparation of 4-amino-substituted tetrahydropyrimido[4,5-d]azocines containing an aromatic pyrimidine fragment has been developed. It was established that tetrahydropyrido[4,3-d]pyri-midines are cleaved by the action of activated alkynes with the formation of 6-vinylpyrimidines.

Synthesis of hexahydro[1,4]diazocino[7,8,1-jk]carbazoles and 1-methoxy-9-(β-vinylethylamino)ethylcarbazoles

3-Ethylhexahydropyrazino[3,2,1-jk]carbazole is converted into hexahydro[1,4]diazocino[7,8,1-jk]carbazoles by the action of methyl propiolate and acetylacetylene in acetonitrile and into 1-methoxy9-(β-vinylethylamino)ethylcarbazoles by the action of acetylenedicarboxylic ester and methyl propiolate in methanol. 3-Benzyl-substituted pyrazinocarbazole does not react with alkynes.

Methyl (9aR*,10S*,11R*,13aS*,13bS*)-9-oxo-6,7,9,9a,10,11-hexa­hydro-5H,13bH-11,13a-ep­oxy­pyrrolo­[2′,1′:3,4][1,4]diazepino[2,1-a]isoindole-10-carboxyl­ate

The title compound, C17H18N2O4, is the methyl ester of the adduct of intramolecular Diels–Alder reaction between maleic anhydride and 1-(2-furyl)-2,3,4,5-tetrahydro-1H-pyrrolo[1,2-a][1,4]diazepine. The molecule comprises a fused pentacyclic system containing four five-membered rings (viz. pyrrole, 2-pyrrolidinone, tetrahydrofuran and dihydrofuran) and one seven-membered ring (1,4-diazepane). The pyrrole ring is approximately planar (r.m.s. deviation = 0.003 Å) while the 2-pyrrolidinone, tetrahydrofuran and dihydrofuran five-membered rings have the usual envelope conformations. The central seven-membered diazepane ring adopts a boat conformation. In the crystal, molecules are bound by weak intermolecular C—H⋯O hydrogen-bonding interactions into zigzag chains propagating in [010]. In the crystal packing, the chains are stacked along the a axis.