Synthesis of Tetrahydro-1H,7H-benzo[ij]quinolizine-1,7-dione Derivatives

Tetrahydro-1H,7H-benzo[ij]quinolizine-1,7-diones have been obtained by the cyclization of N-alkoxyphenyl-N-(2-carboxyethyl)--alanines. Fission of the ester bond occurs on cyclization of N-(4-ethoxyphenyl)-N-(2-carboxyethyl)--alanine, but the cyclization of the 3,4-dialkoxyphenyl derivative leads to the formation of 9-alkoxy-8-hydroxy-2,3,5,7-tetrahydro-1H,7H-benzo[ij]quinolizine-1,7-diones. The corresponding dioximes and diphenylhydrazones were obtained.     

Synthesis and reactions of 2-hydroxy-4-oxo-4-(2,3,5,6-tetrafluoro-4-methoxyphenyl)-but-2-enoic acid methyl ester

2-Hydroxy-4-oxo-4-(2,3,5,6-tetrafluoro-4-methoxyphenyl)-but-2-enoic acid methyl ester (1) was synthesized by the reaction of pentafluoroacetophenone with dimethyl oxalate in the presence of sodium methylate. Subsequently, reactions of compound 1 with aniline, o-phenylenediamine, and o-aminophenol were investigated. In addition, the thermal cyclization of ester 1 was studied and led to the formation of 5,6,8-trifluoro-7-methoxy-4-oxo-4H-chromene-2-carboxylic acid methyl ester (6) due to nucleophilic substitution of the 3-fluoro group. Hydrolysis of compound 1 and subsequent cyclization by treatment with SOCl₂ gave 5-(2,3,5,6-tetrafluoro-4-methoxyphenyl)-furan-2,3-dione (3). Thermal decarbonylation of compound 3 under mild conditions resulted in the formation of 3-(2,3,5,6-tetrafluoro-4-methoxyphenyl)-propene-1,3-dione (4) which dimerized to pyranone 5.     

Biomimetic Synthesis of 5,6-Dihydroxyindole-2-Carboxylic Acid and of its Benzyl Ester

Benzyl 5,6-dihydroxyindole-2-carboxylate 3 and the free acid 4 were synthesized by oxidative cyclization of dopa benzyl ester with ceric ammonium nitrate and subsequent removal of the benzyl group by hydrogenation.     

Synthesis and intramolecular cyclization of 2‐methylsulfany‐4‐oxo‐3(4H)‐quinazolinyl)acetohydrazide

Treatment of ambident sodium salt of 2‐methylsulfanyl‐4(3H)‐quinazolinone with methyl bromoacetate resulted in N₍₃₎‐alkyl ester formation. Reaction of the resulted ester with hydrazine hydrate gave 2‐methylsulfanyl‐4‐oxo‐3(4H)‐quinazolinyl)acetohydrazide, which underwent intramolecular cyclization under heating in dimethylformamide to give 1‐aminoimidazo[2,1‐b]quinazoline‐2,5(1H,3H)‐dione. The latter took place in acylation reaction and in condensation with aromatic aldehydes.     

Reactivity of (2‐methylsulfanyl‐4‐oxo‐6‐phenyl‐4h‐pyrimidin‐3‐yl)‐acetic acid methyl ester towards hydrazine hydrate and benzylamine

The title ester 1 reacted with hydrazine hydrate to give hydrazide 2 , which underwent intramolecular cyclization to yield 1‐amino‐7‐phenyl‐1H‐imidazo[1,2‐a]pyrimidine‐2,5‐dione ( 3 ) or took place in a substitution reaction with benzylamine to form N‐benzyl‐2‐(2‐benzylamino‐4‐oxo‐6‐phenyl‐4H‐pyrimidin‐3‐yl)‐acetamide ( 4 ). The reaction of ester 1 with benzylamine gave corresponding amide 7 , disubstituted derivative 4 or 1‐benzyl‐7‐phenyl‐1H‐imidazo[1,2‐a]pyrimidine‐2,5‐dione ( 8 ) depending on the reaction conditions.     

Carbolines

The reaction of tert-butyl (3-indolyl)carbinol with potassium cyanide yielded a nitrile which was reduced to-tert-butyltryptamine. 1-Methyl-4-tert-butyl--carboline was prepared by cyclization of the acetyl derivative of this amine with subsequent dehydrogenation. An attempt to obtain this compound through 4-(3-indolyl)-5,5-dimethyl-2-hexanone was unsuccessful.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 621–622, May, 1971.     

Synthesis of cyclic sulfides

Two isomers of 2,3-dimethyl-1-thiahydrindane and two isomers of 4-methyl-1-thiadecali were obtained by the reaction of cyclohexene episulfide with crotylmagnesium bromide and subsequent cyclization of the resulting 2-(-methyl--propenyl)-1-cyclohexanethiol by the action of 75% sulfuric acid and UV irradiation.See [3] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 622–625, May, 1972.     

(±)‐2,3‐dialkyl‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters by a tandem reduction‐reductive amination reaction

A series of 2‐methyl‐2‐(2‐nitrobenzyl)‐substituted β‐keto ester derivatives has been subjected to reductive cyclization under hydrogenation conditions to assess the importance of the ester group position on the diastereoselectivity of the process. Hydrogenation over 5% palladium‐on‐carbon at 4 atmospheres pressure resulted in formation of (±)‐2,3‐dialkyl‐1,2,3,4‐tetrahydroquinoline‐3‐carboxylic esters with a preference for the product isomer having the C2 alkyl cis to the C3 ester. The product ratios were synthetically useful (6‐16:1), but less than that observed in cyclizations to prepare (±)‐2‐alkyl‐1,2,3,4‐tetrahydroquinoline‐4‐carboxylic esters. The reduced selectivity in the current reactions has been rationalized in terms of the greater conformational mobility around the ester bearing carbon, which decreases the ability of the ester to sterically influence the addition of hydrogen to the final imine intermediate.     

A new synthesis of alkaloid (S)‐3‐hydroxypiperidin‐2‐one and its O‐TBS protected derivative

From the known lactone (S)‐ 4 , easily derived from L‐glutamic acid, a scalable approach to chiral building block O‐silylated 3‐hydroxypiperidin‐2‐one 3 and alkaloid 1 was achieved in five and six‐steps respectively. The key steps are a chemoselective amidation of lactone‐ester 5 and a one‐pot reductive borane‐decomplexation, N‐debenzylation and cyclization.     

Fluorinated [1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidines and [1,2,4]triazolo[5,1-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazines*

The reaction of 3-R-5-amino-1,2,4-triazoles with the ethyl ester of 2-fluoroacetoacetic acid gave 2-R-fluoro[1,2,4]triazolo[1,5-a]pyrimidin-7(4H)-ones. The reaction of a 3-R-1,2,4-triazolyl-5-diazonium salt with the ethyl ester of 2-fluoroacetoacetic acid and subsequent cyclization of the triazolylhydrazones lead to 7-R-3-fluoro[1,2,4]triazolo[5,1-c][1,2,4]triazin-4(1H)-ones.     

Investigations in the Area of Amines and Ammonium Compounds. 237. Synthesis of 2,2-Dialkyl-4-Hydroxymethylbenzo[f]isoindolinium and 2,2-Dialkyl-4-hydroxymethylisoindolinium Salts

The ability of the 4-hydroxy-2-butynyl group to participate as ,-unsaturated fragment in base-catalyzed intramolecular cyclization was established. 2,2-Dialkyl-4-hydroxymethylbenzo[f]isoindolinium and 2,2-dialkyl-4-hydroxymethylisoindolinium salts were obtained by the cyclization of dialkyl(4-hydroxy-2-butynyl)(3-phenylpropargyl)- or dialkyl(4-hydroxy-2-butynyl)(3-alkenylpropargyl)ammonium salts.     

Investigations in the imidazole series LXXII. Synthesis of naphth[1,2-d]imidazo[3,2-b]-3-thiazolidone and its derivatives

Naphth[1,2-d]imidazo[3,2-b]-3-thiazolidone and its methyl homolog were synthesized by the reaction of 2-mercaptonaphth[1,2-d]imidazole with chloroacetic and -chloropropionic acids with subsequent cyclization of the naphth[1,2-d]imidazole-2-mercaptoacetic acids. The reactions of the first of them at the methylene group with aldehydes, nitroso compounds, and benzenediazonium salts were studied; the corresponding arylidene and azomethine derivatives of naphthimidazo-3-thiazolidone and the arylhydrazones of naphth[1,2-d]imidazo[3,2-b]thiazoline-2,3-dione were obtained. The arylidene derivatives of naphthimidazo-3-thiazolidone were also obtained by the reaction of naphthimidazole-2-mercaptoacetic acid or its methyl ester with aldehydes or (in one step) by the reaction of 2-mercaptonaphth[1,2-d]imidazole with chloroacetic acid and carbonyl compounds.See [1] for communication LXXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 399–402, March, 1972.     

Pyrido[2,3-g]quinolines

The heretofore unknown sym-octahydro-4,9-dioxopyrido[2,3-g]quinoline was synthesized by carboxyethylation of dimethyl 2,5-diaminoterephthalate with -propiolactone with subsequent hydrolysis of the resulting 2,5-bis(-carboxyethylamino)terephthalic acid ester and cyclization of 2,5-bis(-carboxyethylamino)terephthalic acid. The structure of the product was confirmed by the UV and IR spectra and also by reduction to the known sym-octahydropyrido [2,3-g]quinoline.See [7] for preliminary communication.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1535–1537, November, 1970.     

Synthesis of 6- and 8-nitroindolizines

A number of 6- and 8-nitroindolizines were synthesized by quaternization of isomeric 2-methylnitropyridines by -halo ketones and subsequent cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7. pp. 922–926, July, 1976.     

Racemic and diastereoselective synthesis of aryl and heteroaryl tetrahydroisoquinolines via the pictet‐spengler reaction

New tetrahydroisoquinolines were synthesized by the Pictet‐Spengler reaction. Influence of a wide range of aryl and heteroaryl aldehydes, was investigated in the cyclization step with 3,4‐dimethoxyphenylethylamine 1 , L‐DOPA 2 and L‐3,4‐dimethoxyphenylalanine methyl ester 3 . Compounds 2 and 3 served as probes to assess the efficiency of two Pictet‐Spengler reactions with respect to their diastereoselectivity, in order to obtain optically active diastereoisomers. Cis‐ and trans‐diastereoisomers were obtained in short reaction times with moderate to good isolated yields (20‐79%). Both nmr and X‐ray analyses confirmed the expected diastereoisomer configurations.     

Synthesis and structure of 2-methyl-6-oxo-7,8-dihydrospiro(benzo[h]-triazolo[3,4-b]quinazoline-7,1′-cyclopentane)

The reaction of 4-amino-3-ethoxycarbonyl-1,2-dihydrospiro(naphthalene-2,1-cyclopentane) with benzoyl isothiocyanate led to the corresponding 4-(N-benzoylthioureido) derivative, the cyclization of which gave 4-oxo-2-thioxo-1,2,3,4,5,6-hexahydrospiro(benzo[h]qquinazoline-5,1-cyclopentane). Condensation of the latter with hydrazine hydrate gave 2-hydrazino-3,4,5,6-tetrahydrospiro(benzo[h] quinazoline-5,1-cyclopentane), which formed 6-oxo-1H-7,8-dihydrospiro(benzo[h] triazolo[3,4-b] quinazoline7,1-cyclopentane) in reaction with orthoformice ester. Methylation of the product with methyl iodide led to its 2-methyl derivative.Communication 1, see ref. [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 658–662, May, 2000.     

Indole derivatives CI. Synthesis and biological activity of some tryptamines

The cyclization of hydrazones obtained by coupling of diazonium salts with ethyl-acetyl--phthalimidovalerate gives ethyl 5-substituted-3-(2-phthalimidoethyl)indole-2-carboxylates, the successive hydrolysis and decarboxylation of which make it possible to obtain 5-substituted tryptamines. The synthesized hydroxyethyl ester of serotonin was found to have pronounced antiradiation action.See [1] for communication C.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1496–1501, November, 1974.     

Protoberberines from Reissert-Compounds. Part IX [1]. An Alternative Approach to Dibenzoquinolizine- and Isoquinonaphthyridin-13a-carboxylic Acids, a Novel Synthesis of Alangimarine

3,4-Dihydroisoquinoline-Reissert-compounds were alkylated to 1-benzyl- and 1-picolyl-derivatives, which in turn could selectively be hydrolized yielding various carboxylic acids, among others certain amino acids related to 3,4-deoxynorlaudanosoline carboxylic acid (DNLCA). These on treating with ethanolic KOH underwent cyclization to dibenzoquinolizine- and isoquinonaphthyridine-13a-carboxylic acids. Alternatively this cyclization also could be achieved by a more convenient one-pot procedure starting from the same dihydro-Reissert-compounds. Thermal decarboxylation afforded among others the alangia alkaloids alangimarine and dihydroalangimarine.     

Synthesis of penicillin derivatives and study of their cytotoxic properties

By the interaction of heterocyclic thiols with sulfoxides of 6,6-dihydro- and 6-chloropenicillanates, derivatives of 4-heteryldithio-2-azetidinones have been synthesized, as well as products of their cyclization to form 2-heterylthiomethyl-and 2-halomethyl-substituted penicillanates and an ester of 3-chloro-3-methyl-7-chlorocepham-4-carboxylic acid. Also, the desulfurization of 6-chloropenicillanate by Raney nickel has been accomplished. For the substances that have been synthesized, a direct relationship has been established between the intensity of their cytotoxic actionin vitro with respect to tumor cells and the influence of these compounds on the intracellular generation of nitric oxide radicals.Latvian Institute of Organic Synthesis, Riga LV-1006, Translated from Khimiya Geterosiklicheskikh Soedinenii, No. 11, pp. 1494–1503, November, 1998.     

The Synthesis of Hydronaphthalenes from m-Toluic Acid via Cyclization of Thioacetal Monosulfoxides

We recently developed a convenient route to hexahydronaphthalenols such as 5 (R=CO₂CH₃ or CH₃) starting from m-toluic acid (1)¹. The key features of the route involved reduction-alkylation of the toluic acid to the dihydro derivative 2 ², subsequent deprotection and oxidation of the side chain primary alcohol, and acid-catalyzed cyclization of the resulting aldehyde 4. In the case of the dimethylnaphthalenols 5 (R=CH₃), conversion of the angular carboxylic function to the methyl group was effected prior to cyclization via reduction of the p-toluenesulfonic ester of the neopentyl alcohol 3 (R=CH₂OH) using lithium triethylborohydride³.