Über Tetrahydrospiro [cyclohexan-1,4′(1′H)-chinazolin]-2′(3′H)-one

Zusammenfassung Cyclohexanon bzw. Cyclopentanon sowie ihre durch Aldolreaktion entstehenden Dimeren reagieren mit Harnstoff im sauren Medium zu 5,6,7,8-Tetrahydrospiro[cyclohexan-1,4(1H)-chinazolin]-3(2H)-onen (2) bzw. zum Dihydrospiro-(cyclopentan-1,4(1H)-5H-cyclopenta[d]pyrimidin)-2(3H)-on (10). Substituierte Harnsotoffe geben Gemische der isomeren 5,6,7,8-Tetrahydro- und 4a,5,6,7-Tetrahydroverbindungen (2, 3) bzw. 6,7-Dihydro-tH- und 5,6-Dihydro-4aH-verbindungen (10, 11). Charakteristisch für2 (3),10 (11) ist die Reaktivität der Kernstellen 8 bzw. 7 gegenüber elektrophilen Agentien (2f-v, 3f-j, 9 a-i, 10 d-f). Äthylmalonsäurebis-trichlorphenylester bzw. Formaldehyd und prim. Amine führen2 in ein partiell hydriertes 1H-Pyrido[3,2,1-ij]chinazolintrion (6) bzw. 1H-Pyrimido[5,6,1-ij]chinazolinon (7) über. Die 1-Alkylverbindungen (2) geben mit Formaldehyd und primären Aminen Hexahydro-8a-hydroxy-4a,8-propanospiro-(cyclohexan-1,4(1H)-pyrido[4,3-d]pyrimidin)-2(3H)-one (8).

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Heterocycles, XXV: tetrahydrospiro [cyclohexane-1,4(1H)-quinazoline]-2(3H)-ones

Cyclohexanone and cyclopentanone, resp., as well as their dimers (formed by aldol reaction) react with urea in the presence of acids to 5,6,7,8-tetrahydrospiro[cyclohexane-1,4-(1H)-quinazoline]-3(2H)-ones (2) and to the dihydrospiro-(cyclopentane-1,4(2H)-5H-cyclopenta[d]pyrimidine)-2(3H)-one (10), resp. Substituted ureas give the isomeric 5,6,7,8-tetrahydro- and 4a,5,6,7-tetrahydro compounds (2, 3), and 6,7-dihydro-5H- and 5,6-dihydro-4aH-compounds (10, 11), resp. Characteristic for2 (3),10 (11) is the reactivity of the nuclear places 8 and 7 with electrophilic agents (2f-v, 3f-j, 9a-i, 10d-f). Ethylmalonic acid bistrichlorophenylester resp. formaldehyde and primary amines react with2 to the partially-hydrogenated 1H-pyrido[3,2,1-ij]-quinazolinetrione (6) and 1H-pyrimido[5,6,1-ij]-quinazolinone (7), resp. The 1-alkyl compounds (2) give with formaldehyde and primary amines hexahydro-8a-hydroxy-4a, 8-propanospiro(cyclohexane-1,4-(1H)-pyrido[4,3-d]pyrimidine)-2(3H)-ones (8).

     

1-Aryl-6-azauracile, 5. Mitt.: Die Synthese von 1-(β-Pyridyl)-6-azauracil-5-carbonsäure und einiger ihrer Derivate

Zusammenfassung Analog wie in vorherigen Mitteilungen^1–4 wurden -Pyridyl-hydrazono-cyanacetylcarbamidsäureäthylester (1), 1-(-Pyridyl)-5-cyan-6-azauracil (2), 1-(-Pyridyl)-6-azauracil-5-carbonsäure (3), deren Thioamid (4), und Amidoxim (5), welches in 1-(-Pyridyl)-5-[5-methyl-1,2,4-oxdiazolyl(3)]-6-azauracil (6) überge-führt wurde, hergestellt.

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-Pyridylhydrazono-cyanacetylcarbamic acid ethyl ester (1), l-(-pyridyl)-5-cyano-6-azauracil (2), 1-(-pyridyl)-6-azauracil-5-carboxylic acid (3), its thioamide (4) and amidoxime (5) were prepared as described in preceding communications. (5) was converted into l-(-pyridyl)-5-[5-methyl-1,2,4-oxdiazolyl(3)]-6-azauracil (6).

     

Spaltungen mittels Diazoniumverbindungen und Chinonimidchlorid, 6. Mitt.: Über Hydroxychalkone

Zusammenfassung Es wird über die Reaktion verschieden methylsubstituierter 4-Hydroxychalkone mittels Chinonimidchlorid berichtet und gezeigt, daß die Ausbeute an 2,6-Dimethylphenol-indophenol bei der Spaltung von 4,4-Dihydroxy-3,5,3-trimethylchalkon (VII) am RingB dreimal so groß ist als beim 4,4-Dihydroxy-3,3,5-trimethylchalkon (III) am RingA.

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The reaction between several methyl-4-hydroxy-chalkones and p-benzoquinone-monochloroimine has been studied. It has been shown that the yield of 2.6-dimethylphenol-indophenol from the cleavage of 4.4-dihydroxy-3.5.3-trimethyl-chalkon (VII) at ringB is three times the yield resulting from the cleavage of 4.4-dihydroxy-3.3.5-trimethylchalkon (III) at ringA.

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Herrn Prof. Dr.H. Bretschneider zum 60. Geburtstag gewidmet.     

Synthesis of new pyridazino[4′,3′:4,5]-thieno[3,2-d]-1,2,3-triazine and pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Summary 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (2), 3-substituted 8,9-diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-ones (3a–c), 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (4), 8-chloro-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (5), 8-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazines (6a–h) and 7-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-ones(7a–c) were synthesized from 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxamide (1).

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Synthese neuer Pyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-und Pyrimido[4,5:4,5]thieno[2,3-c]pyridazin-Derivate

Zusammenfassung Folgende Verbindungen wurden ausgehend von 5-Amino-3,4-diphenylthieno[2,3-c]pyridazin-6-carboxamid (1) synthetisiert: 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-on (2), 3-substituierte 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (3a–c), 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8[7H]-on (4), 8-Chlor-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin (5), 8-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (6a–h) und 7-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (7a–c).

     

Synthesen in der Pyridazin-Reihe, 31. Mitt.: Über einige neue polycyclische Azolo- und Azinopyridazine

Zusammenfassung Synthesen von verschiedenen neuen polyazaheterocyclischen Systemen, wie 11H-Imidazo[1,22,3]pyridazino[6,1-b]-chinazolin-11-on (3), 11H-s-Triazolo[4,32,3]pyridazino[6,1-b]chinazolin-11-on (4), der Isomeren 4H-Pyrido[2,34,5]-pyridazino[6,1-c]-as-triazin (6) und 4H-Pyrido[3,24,5]-pyridazino[6,1-c]-as-triazin (9), Pyrido[3,24,5]pyridazino[1,6-b]benzimidazol (14) sowie Pyrido[3,24,5]-s-triazolo[4,32,3]pyridazino[1,6-a]benzimidazol (15) werden beschrieben.

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Syntheses of pyridazines, XXXI: Some new polycyclic azolo and azino-pyridazines

Syntheses of several new polyazaheterocyclic systems are described, i.e. 11H-Imidazo[1,22,3]pyridazino[6,1-b]quinazolin-11-one (3), 11H-s-Triazolo[4,32,3]pyridazino[6,1-b]quinazolin-11-one (4), the isomeric 4H-Pyrido[2,34,5]pyridazino[6,1-c]-as-triazine (6) and 4H-Pyrido[3,24,5]pyridazino[6,1-c]-as-triazine (9), Pyrido[3,24,5]pyridazino[1,6-b]-benzimidazole (14) and Pyrido[3,24,5]-s-triazolo[4,32,3]pyridazino[1,6-a]benzimidazole (15).

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Heterocyclen, 69. Mitt.     

Synthetic studies in the field of chlorobium chlorophyll

By the condensation of -halogenomethyl derivatives of pyrroles with -unsubstituted pyrroles the synthesis of the following unsymmetrical dipyrrolylmethanes has been effected: 5-benzyloxycarbonyl-5-ethoxycarbonyl-3, 3-di(-methoxycarbonylethyl)-4,4-dimethyl-2,2-dipyrrolylmethane (IIIa), 5-benzyloxycarbonyl-5-ethoxycarbonyl-3-(-methoxycarbonylethyl)-4, 4-diniethyl-3-n-propyl-2,2-dipyrrolylmethane(IIIb), 3-acetyl-5-benzyloxycarbonyl-4-ethyl-5-methoxycarbonyl-3, 4-dimethyl-2,2-dipyrrolylmethane (IIIc), and 3-bromo-5-benzyloxycarbonyl-4-ethyl-5-methoxycarbonyl-3, 4-dimethyl-2,2-dipyrrolylmethane (IIId). Hydrogenation of the unsymmetrical dipyrrolylmethanes IIIa, b, c, and d has given the corresponding monocarboxylic acids IVa, b, c, and d. The formylation of the dipyrrolylmethanemonocarboxylic acid IVa has given 5-ethoxycarbonyl-5-formyl-3,3-di(-methoxycarbonylethyl)-4, 4-dimethyl-2,2-dipyrrolylmethane (V).For communication II, see [1].Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 8, pp. 1045–1047, August, 1970.     

1,2-Dimethylimidazobenzo-1′, 2′, 3′-thiadiazoles and derived cyanine dyes

New tricylic heterocyclic systems and their methyl derivatives are synthesized. They are 2-methylimidazo[5, 4-e]benzo-1, 2, 3-thiadiazole, 2-methylimidazo[5, 4-g]benzo-1, 2', 3-thiadiazole, 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole, and 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole. Quaternary salts of the 1, 2-dimethyl derivatives are used to prepare symmetrical and unsymmetrical trimethinecyanines and dimethinemerocyanines containing rhodanine groups. The absorption maxima of the dyes are displaced towards the long wavelength region compared with imidacarbocyanines. It is shown that when 1, 2-dimetnyl-5-aminobenzoimidazole is thiocyanated, the thiocyano group enters the benzoimidazole ring at position 4, and that 1, 2-dimethylimidazo[5, 4-e] benzo-1, 2, 3-thiadiazole is less basic than its isomer 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole.     

Study of furan compounds

Research on synthesis of polycyclic spirans of the 1, 6-dioxaspiro-[4, 4]nonane group is continued. Electrolysis of methanol solutions of 2-furylcyclopentanol, 2-(5-methyl-furfuryl)cyclopentanol, and 2-furfuryl-1-indanol, gives, by intramolecular alkoxylation, spiro{perhydrocyclopenta[b]furan-2, 2-(5dihydrofuran)}, spiro{perhydrocyclopenta[b]furan-2, 2-(5-methoxy-5-methyl-2, 5-dihydrofuran)}, and spiro{2, 3, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-(5-methoxy-2, 5-dihydrofuran)}, hitherto undescribed in the literature. Depending on the conditions, catalytic hydrogenation of these gives: spiro{perhydiocyclopenta[b]furan-2, 2-(5-methoxytetrahydrofuran)}, spiro{2, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-(5-methoxytetrahydrofuran)}, spiro{perhydrocyclopenta[b]furan-2, 2-tetrahydrofuran}, and spiro{2, 3, 3a, 8b-tetrahydro-4H-indeno[1, 2-b]furan-2, 2-tetrahydrofuran}.For Part XXXI see [1].     

9-(2′,5′-Dimethyl-4′-pyridyl)fluorene in syntheses of fluorospirodihydrofuropyridine and pyridofluoranthene

1,2,5-Trimethyl-4-(9-fluorenylidene)piperidine, which is formed by condensation of fluorene with 1,2,5-trimethyl-4-piperidone, is converted catalytically to 9(2,5-dimethyl-4-pyridyl)fluorene, from which 2-methylpyrido[4,5-a]fluoranthene and its demethylated analog were obtained by catalytic dehydrocyclization. Oxidation of 9-(2,5-dimethy1-4-pyridyl)fluorene gave 9-(2,5-dimethyl-4-pyridyl)9-fluorenol and fluorene-9-spiro-4-(6-oxo-2-carboxypyrido[4,5-c]-4-6-dihydrofuran). 6-Methyl-2-phenyl-7-(9-fluorenyl)indolizine was synthesized by the Chichibabin method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1087–1090, August, 1978.     

Convenient synthesis of 5′-methyl-2′-desoxyuridines

A convenient method has been developed for the synthesis of 5-methyl-2-desoxyuridines. Chlorination of 5-O-benzoyl-5-methyluridines with a mixture of Ph₃P and CCl₄ in DMF affords the 2-desoxy-2-chloro-derivatives, which are then reduced with tributyltin hydride. The crystalline 5-O-benzoyl-5-methyl-2-desoxyuridines were obtained in overall yields of 40–60%. In a similar way, 5-O-benzoyluridine has given 5-O-benzoyl-2-desoxyuridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246–248, February, 1989.     

Diacetylenic Derivatives of Fe2(CO)6(μ-EE′): Spectroscopic Investigations of Fe2(CO)6{μ-EC(H) = C(C≡ CMe)E′} (E = E′, E ≠ E′; E, E′ = S, Se, Te)

The diacetylenic adducts, Fe₂(CO)₆{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe₂(CO)₆(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (¹H, ¹³C, ⁷⁷Se, and ^l25Te) spectroscopy. Trends in the chemical shifts of ⁷⁷Se and ¹²⁵Te NMR spectra of Fe₂(CO)₆{-EC(H) = C(C CMe)E} with a variation of EE are discussed.     

Nitration,amination, and halogenation of Di-O-methylphloracetophenone

Chlorination of the title compound gave 5- and 3-chloro-2-hydroxy-4,6-dimethoxyacetophenone. The nitration of its acetate, followed successively by reduction, diazotization, and reaction with cuprous chloride, gave the 3-substituted series, 2-acetoxy-4,6-dimethoxy-3-nitroacetophenone, 3-amino-2-hydroxy-4,6-dimethoxyacetophenone, and 3-chloro-2-hydroxy-4,6-methoxyacetophenone, respectively. The orientation of substituents in the products was proved. The amino and chloro members of the isomeric 5-substituted series were availablevia 2-hydroxy-4,6-dimethoxy-5-phenylazoacetophenone, the product of the reaction of the title compound with benzenediazonium chloride.

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Nitrierung, Aminierung und Halogenierung von Di-O-methylphloracetophenon

Zusammenfassung Chlorierung der Titelverbindung gab 5- und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Nitrierung des Acetats, gefolgt von Reduktion, Diazotierung und Reaktion mit CuCl ergab die 3-substituierte Reihe: 2-Acetoxy-4,6-dimethoxy-3-nitroacetophenon, 3-Amino-2-hydroxy-4,6-dimethoxyacetophenon und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Orientierung der Substituenten wird diskutiert. Die Amino- und Chlorderivate der isomeren 5-substituierten Reihe sind über 2-Hydroxy-4,6-dimethoxy-5-phenylacetophenon zugängig, dem Produkt der Reaktion der Titelverbindung mit Phenyldiazoniumchlorid.

     

Synthesis of 2,3,7,8-tetramethyldibenzofuran

3,4,3,4-Tetramethyldiphenyl ether readily forms 2,2-dihalo derivatives on bromination and iodination. Heating 2,2-diiodo-4,5,4,5-tetramethyldiphenyl ether with copper powder or oxidation, of 2,2-dilithio-4,5,4,5-tetramethyldiphenyl ether gives 2,3,7,8-tetramethyldibenzofuran, the structure of which was proved by alternative synthesis from 2,2-dinitroand 2,2-diamino-4,5,4,5-tetramethyldiphenyls.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1597–1599, December, 1972.     

New cardenolides from the leaves ofGomphocarpus fruticosus

Two new glycosides, gomphotin (1) and gomphotoxin (13), and also the known gomphoside (9) have been isolated from the leaves ofGomophocarpus fruticosus. Compounds (1) and (9) contain a 4,6-dideoxyhexosulose residue as the sugar component, and (13) a 6-deoxyhexosulose, which are attached to glycolic OH groups of the aglycons by 3-O-1,2-O-2 (9, 13) and 3-O-1,4-O-2 (1) acetal-ketal bonds. The structures of the new compounds are represented by the names (3-O-1,4-O-2)-(2,3-dihydroxy-4, 6dideoxyhexulosido)-14-hydroxy-5-card-20(22)-enolide* (1) and (3-O-1,2-O-2)-(2,3,4-trihydroxy-6-deoxyhexulosido)-14-hydroxy-5-card-20(22)-enolide* (13).State Scientific Center for Drugs of the Ministry of Health and the National Academy of Sciences of the Ukraine, Kharkov, fax 441118. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 824–832, November–December, 1995. Original article submitted May 22, 1995.     

The quest for a stable silyne, RSi ≡ CR′. The effect of bulky substituents [1]

The two major fundamental obstacles which so far have prevented theisolation of stable silynes, RSiCR (1), are: (a)the existence of more stable isomers, e.g., RRC=Si: (2) and(b) their extremely facile (exothermic) dimerication. The steric andelectronic effects of various substituents R and R (R = alkoxy,alkyl, aryl and silyl; R = alkyl and aryl groups) on the stability ofRSiCR relative to the isomeric RRC=Si:(E(1-2)), and on the energy of dimerization tothe corresponding 1,3-disilacyclobutadienes (E(D)), werestudied computationally using density functional theory (DFT) and theONIOM method. The goal was to find a combination of substituents thatwill make RSiCR more stable than RRC=Si: and whichwill also prevent its dimerization. For R = R = H,E(1-2)) = 40.7 kcal/mol (i.e., 2 islower in energy than 1), and E(D) = –104.0kcal/mol. 1, R = OH, R = m-Tbt 2,6-bis[bis(silyl)methyl]phenyl, is by 11.1 kcal/mol morestable than the isomeric silylidene 2. However, thedimerization of 1, R = OH, R = m-Tbt remains highlyexothermic (by 101 kcal/mol). 1, R = R = m-Tbt and1, R = (t-Bu)₃Si, R = m-Tbt, are by 5.8 and 2.0kcal/mol, respectively, less stable than the corresponding 2.However, the dimerization of 1, R = (t-Bu)₃Si, = m-Tbt is exothermic by only 12 kcal/mol. For1, R = (t-Bu)₃Si, and R = Tbt 2,6-bis[bis(trimethylsilyl)methyl]phenyl, the corresponding1,3-disilacyclobutadiene dimer 3, dissociates spontaneously.Thus, (t-Bu₃Si)SiCTbt is predicted to be kineticallystable towards both, isomerization to (t-Bu₃Si)TbtC=Si: anddimerization to 3, making it a viable synthetic target. Thereported energies were calculated atB3LYP/6-31G^**//B3LYP/3-21G^*; good agreement is found betweenthe DFT and the ONIOM results.     

Studies of 2,3′-biquinolyl. 6. Regioselectivity of nucleophilic addition of organometallic compounds to 1-aklyl-3-(2-quinolyl)quinolinium halides

Nucleophilic addition of organometallic lithium and magnesium compounds to 1-alkyl-3-(2-quinolyl)quinolinium cations produces a mixture of the corresponding 1-alkyl-2-R-1,2-dihydro-2,3-biquinolyls and 1-alkyl-4-R-1,4-dihydro-2,3-biquinolyls. The portion of the latter decreases with increasing hardness of the organometallic compound.For No. 5, see [1].Stavropol State University, Stavropol'355009, Russian Russian Chemical Technology University Moscow 125190 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 919–923, July, 1999.     

Synthesis of obtusinin and 7-(3′-hydroxymethylbut-2′-enyloxy)-6-methoxy-2H-1-benzopyran-2-one

Obtusinin (1) has been synthesised by the reaction of 6-methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-one (3) with OsO₄. Synthesis of 7-(3-hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-one (2) has been achieved by the regiospecific oxidation of3 with SeO₂ followed by reduction of the formed aldehyde with KBH₄.

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Synthese von Obtusinin und 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on

Zusammenfassung Obtusinin (1) wurde über 6-Methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-on (3) mit OsO₄ synthetisiert. Die Darstellung von 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on (2) wurde mittels regioselektiver Oxidation von3 mit SeO₂, gefolgt von Reduktion des gebildeten Aldehyds mit KBH₄, bewerkstelligt.

     

1,4-bis(4′-hydroxy-1′,2′,5′-trimethyl-4-piperidyl)-1,3-butadiyne and its derivatives

1.4-Bis(4-hydroxy-1,2,5-trimethyl-4-piperidyl)-1.3-butadiyne has been synthesized from the individual isomers of 4-ethynyl-1,2,5-trimethyl-4-piperidol. Hydrogenation, bromination, and cleavage have given, respectively, 1,4-bis(4-hydroxy-1,2,5-trimethyl-4-piperidyl)butane, 1,4-bis(4-nydroxy-1,2,5-trimethyl-4-piperidyl)-1,2,3,4-tetrabromo-1, 3-butadiene, and 4-(1,3-butadiynyl)-1,2,5-trimethyl-4-piperidol.     

Synthesis of some 5′-O-amino acid derivatives of uridine as potential inhibitors ofUDP-glucuronosyltransferase

Summary In an attempt to develop potential inhibitors ofUDP-glucuronosyltransferase, some 5-O-amino acid derivatives of uridine were synthesized. N-protectedL-amino acids were coupled at the 5-O-position of 2,3-O-isopropylideneuridine by esterification employing the method of symmetrical anhydrides in presence of 4-dimethylaminopyridine, 5-O-(N-benzyloxycarbonyl-O-tert.butyl-L-threonl)-23-O-isopropylideneuridine (1), 5-O-(N-tert.butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylideneuridine and (2), 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (3), and 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (4) were obtained in good yield after column chromatography on silica gel. The treatment of2 withTFA/CH₂Cl₂ (6:1) at room temperature for 30 min led to a selective removal of theBoc group without deblocking of the 2,3-O-isopropylidene group of uridine. Treatment of2 withTFA/H₂O (5:1) at room temperature for 1 h, however, released bothBoc and 2,3-isopropylidene groups. TheZ group of1 was deprotected by catalytic hydrogenolysis over 10% Pd/C/ammonium formate.

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Synthese von 5-O-Aminosäurederivaten des Uridins als potentielle Inhibitoren derUDP-Glukuronosyl-Transferase

Zusammenfassung In einem Versuch, potentielle Inhibitoren derUDP-Glukuronosyl-Transferase zu entwickeln, wurden einige 5-O-Aminosäurederivate des Uridins synthetisiert. N-GeschützteL-Aminosäuren wurden durch Veresterung mit der 5-O-Position des 2,3-isopropylidenuridins gekuppelt (Methode der symmetrischen Anhydride in der Gegenwart von 5-Dimethylaminopyridin). Solcherweise wurden 5-O-(N-Benzyloxycarbonyl-O-tert.butyl-L-threonly)-2,3-O-isopropylidenuridin (1), 5-O-(N-tert.Butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylidenuridin (2), 5-O-(N-tert.Butyloxycarbonyl-L-leucyl)-2,3-O-isopropylidenuridin (3) und 5-O-(N-tert.Butyloxycarbonyl-L-valyl)-2,3-O-isopropylidenuridine (4) nach Säulenchromatographie (Kieselgel) in guter Ausbeute hergestellt. Die Behandlung von2 mitTFA/CH₂Cl₂ (6:1) bei Zimmertemperatur (30 min) führte zu einer selektiven Abspaltung derBoc-Gruppe ohne Deblockierung der 2,3-O-Isopropylidengruppe des Uridins. Eine Behandlung von2 mitTFA/H₂O (5:1) bei Zimmertemperatur für 1 Stunde führte hingegen zur Abspaltung sowohl derBoc als auch der 2,3-O-Isopropylidengruppe. DieZ-Gruppe von1 wurde durch katalytische Hydrogenolyse auf 10% Pd/C/Ammoniumformiat abgespalten.

     

Untersuchung des Zerfalls verschiedener Azoinitiatoren in Lösung

The decomposition of various symmetric and unsymmetric azo-initiators (1,1-dichloro-1,1-diphenyl-1,1-azoethane, 2,2-dichloro-2,2-azopropane, 1,1-dichloro-1,1-azocyclohexane, 2,2-diacetoxy-2,2-azopropane, 1,1-diacetoxy-1,1-diphenyl-1,1-azoethane, 1,1-diacetoxy-1,1-azocyclohexane, 2,2-dipropionoxy-2,2-azopropane, 2,2-dicapronoxy-2,2-azopropane, 4,4-dimethyl-1,4-azobutyrolactone, azoisobutyronitrile, 2-t-butylazo-2-cyanobutan, 2-t-bytylazo-1-cyanocyclohexan) in solution was studied in dependence of temperature. Volumetry and differential-scanning-calorimetry (DSC) were used to determine decomposition rates; first order kinetics was found in all cases.