Synthesis and spectral properties of coumaronyl-substituted benzo[f]quinolines

Condensation of arylidene-2-naphthylamines with 2-acetylbenzofuran (2-acetylcoumarone) was used for the first time to synthesize 1-(2-coumaronyl)-3-arylbenzol[f]quinolines containing two different heteroatoms — N and O — in the molecule. The IR, UV, ESR and mass spectra of the compounds obtained were studied.Institute of Organophysical Chemistry, Belorussian Academy of Sciences, Minsk 220072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 960–964, July, 1996. Original article submitted April 18, 1996.     

Nitriles in organic synthesis: A novel synthesis of benzo[h]pyrimidino[1,2-c]-pyridazinone and hydrazonobut-2-enonitrile derivatives

A new synthesis of benzo[h]pyrimidino[1,2-c]pyridazinones via coupling diazotised anthranilic acid with 1-phenylethylidenemalononitrile ( 1 ) is reported. Synthesis of new 1-antipyrin-4-yl and 1-pyrazol-5-ylpyridazine derivatives utilizing 1 as starting material is also described.     

Substituted 2- and 4-benzylpyridines in the synthesis of benzo[g]quinolines and benzo[g]isoquinolines

Nitrogen-containing heterocyclic analogs of anthracene, viz., benzo[g]isoquinolines and benzo[g]quinolines, were obtained by dehydrocyclization on a K-16 catalyst of mixtures of methyl-substituted 2- and 4-benzylpyridines with methyl groups in various positions of the pyridine and benzyl rings, which are formed by benzylation of -picoline, as well as pyridine, by the Ladenburg method. The spectral characteristics of the synthesized compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 673–676, May, 1980.     

A new rapid multicomponent domino reaction for the formation of functionalized benzo[h]pyrazolo[3,4-b]quinolines

A new multicomponent domino reaction for rapid and regioselective synthesis of highly functionalized benzo[h]pyrazolo[3,4-b]quinolines has been established. The reaction can be conducted by using readily available and inexpensive substrates under microwave irradiation within short periods of 10-26 min. Good to excellent chemical yields (61-91%) and complete regioselectivity have been achieved for 22 examples. Tedious work-up procedure can be avoided due to the direct precipitation of products from the reaction solution. The resulting benzoquinolines have been readily converted into quinoxaline-fused benzo[h]isoxazolo[5,4-b]quinoline analogues by treating with benzene-1,2-diamine under microwave irradiation. The structural assignment has been ambiguously confirmed by X-ray analysis. A new mechanism has been proposed for this new multicomponent domino process.     

Synthesis and fluorescence properties of novel benzo[a]phenoxazin-5-one derivatives

Thirteen, benzo[a]phenoxazin-5-one derivatives 3a-m were synthesized from 4-nitrosoaniline hydrochlorides 1a-m and ethyl 1,3-dihydroxynaphthoate 2 and their fluorescence properties were discussed in terms of the electronic effect of substituents. A coupling reaction was carried out with 6-carbethoxy-9-N-(2-hydroxyethyl)-N-methylamino-5H-benzo[a]phenoxazin-5-one (3k) and acetyl-DL-alanine to afford N-[(6-carbethoxy-5-oxo-5H-benzo[a]phenoxazin)-9-yl]-N-methylaminoethylene acetyl-DL-alanine ester (4).     

New approaches to the synthesis of benzo[h]pyrroloisoquinoline derivatives

An effective strategy for the synthesis of benzo[h]pyrrolo[2,1-a]isoquinoline derivatives has been developed. The process can be described as a one-pot domino reaction that consists of an initial Michael addition, intramolecular cyclization, and subsequent transformations leading to the formation of the desired products. A wide range of structurally diverse hydrogenated benzo[h]pyrrolo[2,1-a]isoquinolines were obtained in 34–98% yield. This strategy represents an efficient catalyst-free procedure that allows the synthesis of previously inaccessible compounds.     

A novel synthesis of the benzo[F]quinazoline ring system

An approach to the synthesis of the benzo[f]quinazoline ring system using a preformed pyrimidine is described. A facile cyclization of a ketone function into the 5-position of uracil is the key step in this sequence.     

Synthesis of benzo[g]quinoline derivatives. XI. 2,4-Diamino-substituted benzo[g]quinolines

Previously unknown 2,4-diamino-substituted benzo[g]quinolines were synthesized from 2,4-dihydroxybenzo[g]quinoline.     

Synthesis and spectroscopic properties of novel benzo[a]phenanthridines

Condensation of arylidene-2-naphthylarnines with 5,5-dimethylcyclohexane-1,3-dione (dimedone) gives novel 2,2-dimethyl-5-R-1,2,3,4,5,6-hexahydrobenzo[a]phenanthridin-4-ones. Treatment of azomethines containing an ortho hydroxyl group in the aldehyde fragment gives the corresponding 3,3,6,6-tetramethyl-9-R-1,2,3,4,5,6,7,8-octa-hydroxanthene-1,8-diones. The IR, UV, PMR, and mass spectra of the compounds synthesized have been studied.     

The synthesis of difluoro[1]benzothieno[2,3-c]quinolines and their N-methyl quaternary salts

A series of difluoro[1]benzothieno[2,3-c]quinolines has been prepared by photocyclization of the appropriate carboxamides. The lactams obtained were converted into the corresponding chloro derivatives which were catalytically dechlorinated into the difluoro[1] benzothieno[2,3-c]quinolines. The latter compounds were transformed into the N-methyl quaternary salts.     

The synthesis of substituted [1]benzothieno[2,3-c]quinolines and their N-methyl quaternary salts

Four substituted [1]benzothieno[2,3-c]quinolines 14a-14d were prepared by photocyclization of the appropriate carboxamides 8a-8d to the corresponding [1]benzothieno[2,3-c]quinolin-6(5H)-ones 12a-12d followed by chlorination to 6-chloro[1]benzothieno[2,3-c]quinolines 13a-13d and dechlorination resulting in the title compounds. Treatment of 14a-14d with iodomethane furnished the corresponding N-methyl quaternary salts 5a-5d .     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 2 . Benzo[h][1]benzothieno[2,3-c]quinoline and benzo[h][1]benzothieno[2,3-c]quinoline

The synthesis of two previously unknown unsubstituted heterocyclic ring systems namely, benzo[h][1]benzothieno[2,3-c]quinoline ( 6 ) and benzo[f][1]benzothieno[2,3-c]quinoline ( 12 ) is reported. These two novel ring systems have been assembled by photocyclization of the appropriate amides.     

Synthesis of some benzo[h]quinoline derivatives

Reaction between 6-methoxy-1-tetralone, methyl propiolate and an ammonia-saturated methanolic solution led to 5,6-dihydro-8-methoxybenzo[h]quinolin-2(1H)-one in good yields. Subsequent aromatization, chlorination, substitution and demethylation enabled us to prepare 2-amino-substituted benzo[h]quinoline derivatives. These compounds, which are structurally related to the antitumor benzo[c]phenanthridine alkaloids by deletion of a ring, were tested on cultured murine lymphoblastic leukaemia cells (L1210). Results showed that they are devoid of cytotoxicity.     

A novel route for the synthesis of benzo[b]thiepins

3,4 - Di(methoxycarbonyl) - 5 - pyrrolidinobenzo[b]thiepin 5 is synthesized by a [2+2]cycloaddition of 3 - pyrrolidinobenzo[b]thiephene 3 to dimethyl acetylenedicarboxylate, with subsequent ring opening of the cyclobutene moiety in the intermediate 6,7-di(methoxycarbonyl)-5-pyrrolidino - 2 - thiabenzo[b]bicyclo[3.2.0]hepta - 3,6 - diene 4 (detectable by PMR spectroscopy at ?30°C). Hydrolysis of the pyrrolidino group in 5 affords 3,4 - di(methoxycarbonyl) - 5 - hydroxybenzo[b]thiepin 8. Peracid oxidation of 5 yields the corresponding 1,1-dioxide. The benzo[b]thiepins are thermally unstable and (depending on the substituents) either extrude sulphur or rearrange to a 4-mercapto-1-naphthol, probably via the thianorcaradiene as the intermediate. The kinetics of the latter reaction are discussed. On being irradiated, the benzo[b]thiepins isomerize to 2-thiabenzo[b]bicyclo[3.2.0]hepta-3,6-dienes.     

A new synthesis of benzo[f]ninhydrin

A new four step synthesis of benzo[f]ninhydrin is described. This method utilizes affordable, readily available materials and reagents and is amenable to large scale production.     

Measurement of benzo[a]pyrene,benzo[k]fluoranthene and benzo[g,h,i]perylene by ultraviolet spectroscopy

Microchimica Acta - The technique for determining benzo[a]pyrene, benzo[k]fhuoranthene, and benzo[g,h,i]perylene respectively inμg amounts by UV absorption measurements is described. The...