The chemistry of naphthazarin derivatives

Direct oxidation of naphthazarin with manganese dioxide in conc. H₂SO₄ was found to be a simple and effective method for the synthesis of mompain. For Part 3, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1019–1021, May, 1999.     

The chemistry of naphthazarine derivatives

Based on IR and¹H and¹³C NMR spectroscopic studies, the oxidation product of echinochrome with Ag₂O was assigned the structure of 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone. For part 4, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1607–1609, August, 1999.     

Synthesis and structure elucidation of oxidative coupling products of 2-hydroxy-1,4-naphthoquinones

2,3-Dihydro-3-O-(1,4-naphthoquinon-2-yl)-2-oxo-1,4-naphthoquinones are the products of oxidative coupling of substituted 2-hydroxy-1,4-naphthoquinones (regardless of the presence of peri-hydroxy groups in their structures) under the action of lead dioxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 294—298, February, 2006.     

Chemistry of naphthazarin derivatives 13. Conformational analysis of 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones by quantum chemistry methods

The molecular structures of various conformers of 2-hydroxy-1,4-naphthoquinone; 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones; 2,5,8-trihydroxy-1,4-naphthoquinone; and 3-(alk-1-enyl)-2,5,8-trihydroxy-1,4-naphthoquinones were studied by density functional theory (B3LYP/6-31(d), B3LYP/6-31(d, p)) and ab initio (MP2/6-31G, MP2/6-31(d)) methods. The strengths of the intramolecular hydrogen bonds formed by the β-hydroxy group with the O atom at C(1) and with the double bond π-electrons of the alkenyl substituents in the quinonoid rings were estimated. The compounds studied mainly exist as rotamers with the former-type hydrogen bonds. The splitting of the quinonoid bands of the stretching vibrations of the β-hydroxy group in the IR spectra of 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones and 3-(alk-1-enyl)-2,5,8-trihydroxy-1,4-naphthoquinones in hexane solutions is due to the existence of rotamers formed upon internal rotation of the alkenyl substituent. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1667–1673, October, 2006.     

Chemistry of naphthazarin derivatives. 8. Determination of structures of substituted 2-hydroxy-6(7)-methoxynaphthazarins and 7(8)-hydroxypyranonaphthazarins by IR spectroscopy

A set of substituted 2-hydroxy-6(7)-methoxynaphthazarins and 7(8)-hydroxypyranonaphthazarins were synthesized. The IR spectra of 2-hydroxy-6-methoxynaphthazarins and 7-hydroxypyranonaphthazarins, on the one hand, and of 2-hydroxy-7-methoxynaphthazarins and 8-hydroxypyranonaphthazarins, on the other hand, have the characteristic nonoverlapping intervals of stretching vibration frequencies of the -hydroxy groups. These regularities confirm the structures of cristazarin and 6-methylcristazarin, which are metabolites of lichen Cladonia cristatella.     

Synthesis of thiopheno-quinizarine derivatives

4,11-Dihydroxyanthra[2,3-b]thiophene-5,10-dione (thiophenoquinizarine) and its 3-methyl derivative were obtained by the cyclization of quinizarin-2-yl derivatives of mercaptoacetaldehyde or mercaptoacetone in acid medium. 4,11-Dimethoxy-and 4,11-dibutoxyanthra[2,3-b]thiophene-5,10-dione were synthesized by the alkylation of the hydroxyl group in the synthesized anthrathiophenes with dimethylformamide dimethylacetal or butyl iodide respectively. Radical bromination of 4,11-dimethoxy-3-methylanthra[2,3-b]thiophene-5,10-dione, depending on the amount of N-bromo-succinimide taken, leads to the formation of 3-bromomethyl-or 3-dibromomethyl-4,11-dimethoxy-anthra[2,3-b]thiophene-5,10-diones. The action of sodium acetate on the obtained bromo derivatives with subsequent hydrolysis of the intermediate acetates led to the synthesis of 3-hydroxymethyl-or 3-formyl-4,11-dimethoxy-anthra[2,3-b]thiophene-5,10-diones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1478–1485, October, 2007.     

The reactions of aroylpyruvic acids and their derivatives witho-aminophenyldiphenylmethanol

Aroylpyruvic acids and their methyl esters react witho-aminophenyldiphenylmethanol to form 4-aryl-2-[2-(1-hydroxydiphenylmethyl)phenylamino]-4-oxobut-2-enoic acids and their esters. The α-enamino acids obtained undergo intramolecular heterocyclization in the presence of Ac₂O to affort substituted 4,5-dihydrobenzo[e][1,4]oxazepin-3(1H)-ones. The reaction of 5-arylfuran-2,3-diones witho-aminophenyldiphenylmethanol leads to products of decyclization, 2-(1-hydroxydiphenylmethyl)phenylamides of 4-aryl-2-hydroxy-4-oxobut-2-enoic acid, which upon heating in AcOH or Ac₂O yield 3-aroylacetyl-1,1-diphenyl-1H-benzo[d][1,3]oxazines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2317–2319, November, 1998.     

Synthesis and molecular structure of 4-nitro-9-phenyl-1H-and 9-hydroxy-3-oxo-9-phenyl-2,3-dihydro-9H-indeno-[2,1- c ]pyridines and 3,7-diphenyl-3a, 4,5,6-tetrahydroindeno[2,1- c ]isoxazolo[5,4- d ]pyridine

The 4-nitro derivatives and an oxidation by-product, 9-hydroxy-2-methyl-3-oxo-9-phenyl-2,3-dihydro-9H-indeno[2,1-c]pyridine were obtained by the nitration of N-alkyl-9-phenyl-2,3-dihydro-1H-indeno-[2,1-c]pyridines with sodium nitrite in acetic acid. Their molecular structures were studied by X-ray structural analysis. The product of [2+3] cycloaddition, 5-methyl-3,7-diphenyl-3a, 4,5,6-tetrahydroindeno[2,1-c]isoxazolo[5,4-d]pyridine, was obtained by the interaction of 2-chloro-1-hydroxy-2-phenylazomethine with 2-methyl-9-phenyl-2,3-dihydro-1H-indeno[2,1-c]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1390–1399, September, 2007.     

Reactions of trimethinecyanines of the 1,3-dioxenium series with nucleophiles. The structures of the parent carbocation and of a product of its reaction with methanol

The chemistry and the regioselectivity of alcoholysis, aminolysis, and hydrolysis of symmetrical trimethinecyanine carbenium ions in 4-[3-(2,2-diorganyl-6-phenyl-4H-1,3-dioxen-4-ylidene) prop-1-enyl]-2,2-diorganyl-6-phenyl-1,3-dioxenium perchlorates (4a,b) were investigated. The structures of trimethinecyanine 4,5:4′,5′-bisannelated at the methine chain (3) and of a product of the reaction of nonannelated trimethinecyanine with the methoxide anion were established by X-ray diffraction analysis,¹H NMR spectroscopy, and quantum-chemical calculations (PM3). The nucleophile attacks the mesomeric π-conjugated system of the trimethinecyanine cation selectivily at the C(6) atom of one of the dioxenium fragrments, the second dioxenium ring being deactivated. Alcoholysis affords products of addition of the methoxy group to trimethinecyamines. In the course of aminolysis and hydrolysis, the dioxenium ring that is subjected to the attack eliminates acetone to form 1,3-dioxenylidenepropenylic derivatives of 1,3-enaminoketones and 1,3-ketoenols, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 521–529, March. 1999.     

Domino reactions in water for the stereoselective synthesis of novel spiro dihydro-2′H-[indene-2,3′-thiophen]-1(3H)-ones with three contiguous stereocenters

The domino reactions of (E)-2-(aryl)-2,3-dihydro-1H-inden-1-ones and 1,4-dithiane-2,5-diol in the presence of triethylamine in water stereoselectively afforded a library of 2′-(aryl)-4′-hydroxy-4′,5′-dihydro-2′H-spiro[indene-2,3′-thiophen]-1(3H)-ones. This transformation presumably proceeds via the generation of 2-mercaptoacetaldehyde from 1,4-dithiane-2,5-diol followed by Michael addition–intramolecular aldol sequence with C–C and C–S bond formations and creation of three contiguous stereocenters in a one-pot operation.