Breakdown of Chlorophyll: Partial synthesis of a putative intermediary catabolite. Preliminary communication

The partial synthesis of 10,22-dihydro-4,5-dioxo-4,5-secopheophorbide a ( 1 ) from pheophorbide a methyl ester (2) is described. A regioselective, photooxygenolytic reaction of (pheophorbidato a methyl ester)cadmium(II)( 3 ) provides the entry to the crucial 4,5-secoporphinoid structure in form of the (10,22-dihydro-4,5-dioxo-4,5-seco-pheophorbidato a methyl ester)cadmium(II) ( 4 ). The hydride reduction of this 4,5-dioxo-4,5-secophytoporphyrin ester occurs selectively at the ‘eastern’ meso-position to lead (after demetallation) to 10,22-dihydro-4,5-dioxo-4,5-secopheophorbide a methyl ester ( 5 ). This oxobilin-carbaldehyde has the structure assigned earlier to an ester of an isolation form of the red pigment(s) from Chlorella protothecoides. Hydrolysis of the propanoate ester function of 5, selectively catalyzed by pig liver esterase, then yields the title compound 1 . The red tetrapyrrole 1 may represent an intermediary chlorophyll catabolite in degreening plants.     

A Comparison of Benzo(A)Pyrene-4,5-Epoxide Hydrase Activity in Hamster Embryo Cells,Hepatocytes and Livers Using High-Pressure Liquid Chromatography

Abstract

The benzo(a)pyrene-4,5-epoxide (BP-4,5-epoxide) hydrase activities of intact hamster hepatocytes and embryo cells, and homogenates of these cells as well as of adult liver are compared. The product of the epoxide hydrase (EH) reaction, trans-4,5-dihydro-4,5-dihydroxybenzo(a)pyrene (BP-4,5-diol), was isolated by high-pressure liquid chromatography (HPLC) with a Waters Bondapak C₁₈/Corasil column and acetonitrile-water as the mobile phase. Using this procedure to determine BP-4,5-epoxide hydrase activity in intact cells, it was found that 266 nmoles of BP-4,5-diol/10⁶ cells were produced by hepatocytes while no diol formation was detected with embryo cells. EH activity in the intact hepatocytes was 8-fold greater than in hepatocyte homogenates.     

Synthesis and biological activity of phospholipase C-resistant analogues of phosphatidylinositol 4,5-bisphosphate

The membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is an important regulator in cell physiology. Hydrolysis of PtdIns(4,5)P2 by phospholipase C (PLC) releases two second messengers, Ins(1,4,5)P3 and diacylglycerol. To dissect the effects of PtdIns(4,5)P2 from those resulting from PLC-generated signals, a metabolically stabilized analogue of PtdIns(4,5)P2 was required. Two analogues were designed in which the scissile O-P bond was replaced with a C-P bond that could not be hydrolyzed by PLC activity. Herein we describe the asymmetric total synthesis of the first metabolically stabilized phospholipase C-resistant analogues of PtdIns(4,5)P2. The key transformation was a Pd(0)-catalyzed coupling of a H-phosphite with a vinyl bromide to form the desired C-P linkage. The phosphonate analogues of PtdIns(4,5)P2 were found to be effective in restoring the sensitivity of the TRPM4 channel to Ca2+ activation.     

Application of esca to semi-quantitative surface and state analysis of iron oxides

In order to study oxidation states in the surface analysis of solids, a semi-quantitative ESCA (X-ray photoelectron spectroscopy-XPS and X-ray-excited Auger-electron spectroscopy-XAES) method was proposed. Taking iron-oxygen compounds as examples, the summation or subtraction technique was utilized in the analysis of ESCA spectra to identify the co-ordination type and crystal structure. The "XAES intensity factors" for the lines Cr L(3)M(2,3)M(4,5), Ti L(3)M(2,3)M(4,5) and from Fe L(3)M(4,5)M(4,5) to Zn L(3)M(4,5)M(4,5) were estimated and their occurrence discussed.     

Syntheses, structures, and electrochemical properties of platinum(II) complexes containing di-tert-butylbipyridine and crown ether annelated dithiolate ligands

A series of new platinum(II) complexes containing both 4,4'-di-tert-butyl-2,2'-bipyridine (dbbpy) and the extended tetrathiafulvalenedithiolate ligands have been prepared and characterized. These complexes include [Pt(dbbpy)(C8H4S8)] (1; C8H4S82- = 2-{(4,5-ethylenedithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(ptdt)] (2; ptdt = 2-{(4,5-cyclopentodithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(mtdt)] (3; mtdt = 2-{(4,5-methylethylenedithio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(btdt)] (4; btdt = benzotetrathiafulvalenedithiolate), [Pt(dbbpy)(C8H6S8)] (5; C8H6S82- = 2-{4,5-bis(methylthio)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), [Pt(dbbpy)(3O-C6S8)] (6; 3O-C6S82- = 2-{4,5-dithia-(3',6',9'-trioxaundecyl)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate), and [Pt(dbbpy)(4O-C6S8)] (7; 4O-C6S82- = 2-{4,5-dithia-(3',6',9',12'-tetraoxatetradecyl)-1,3-dithiol-2-ylidene}-1,3-dithiol-4,5-dithiolate). The crystal structures of a new ligand precursor (2-[4,5-dithia-(3',6',9',12'-tetraoxatetradecyl)-1,3-dithiol-2-ylidene]-4,5-bis(2-cyanoethylsulfanyl)-1,3-dithiole, IIIc) and complexes 5-7 have been determined by X-ray crystallography. Complexes 1-7 show intense electronic absorption bands in the UV-vis region due to the intramolecular mixed metal/ligand-to-ligand charge-transfer transition, and they display significant solvatochromic behavior. Redox properties of these compounds have been investigated by cyclic voltammetry, and complex 7 shows a significant response for Na+ ions with a large positive shift of ca. 45 mV.     

The preparation of the benzo[4,5]cyclohepta[1,2-b]pyrazine and benzo[4,5]cyclohepta[1,2-b]quinoxaline systems

Benzo[4,5]cyclohepta[1,2-b]quinoxaIine 2 , benzo[4,5]cyclohepta[1,2-b]pyrazine 3a and benzo[4,5]cyclohepta[1,2-b]quinoxaline 4 were prepared from 4,5-benzotropolone and 1,2-phenylenediamine, ethylenediamine and 1,2-diaminocyclohexane, respectively. Compound 3a was methylated to 3b .     

Synthesis of new ferrocene derivatives with a 4,5-dichloroisothiazole fragment

Conjugates of ferrocene and 4,5-dichloroisothiazole were synthesized, where the ferrocene and isothiazole moieties are linked through various structural fragments. The acylation of ferrocene with 4,5- dichloroisothiazole-3-carbonyl chloride gave (4,5-dichloroisothiazol-3-yl) ferrocenyl ketone; the acylation of aminomethylferrocene furnished the corresponding amide. The esterification of ferrocene-1,1′-dicarboxylic acid with 4,5-dichloroisothiazol-3-yl-methanol resulted in the formation of the corresponding ester. The condensation of 1,1′-diacetylferrocene with 4,5-dichloroisothiazole-3-carbaldehyde afforded ferrocenophane containing 4,5-dichloroisothiazole moieties.     

一步法合成取代-1,2-苯醌类化合物

应用固定化多酚氧化酶催化的氧化-迈克尔加成反应,一步合成了4,5-二取代-1,2-苯醌类化合物:4,5-N,N-二(苯胺基)-1,2-苯醌,4,5-N,N-二(对甲苯胺基)-1,2-苯醌,4,5-N,N-二(间氯苯胺基)-1,2-苯醌,4,5-N,N-二(对溴苯胺基)-1,2-苯醌。用化学法(I_2—KI)进行氧化-迈克尔加成反应也成功地合成了4,5-二取代-1,2-苯醌类化合物。应用紫外光谱方法证明了氧化-迈克尔加成反应的机制。     

Pyrolysis and photolysis of 1-aroylamino-4,5-diaryl-1,2,3-triazoles: Generation and thermal transformations of 4,5-diaryl-1,2,3-triazolyl radicals

The pyrolysis of 1-aroylamino-4,5-diphenyl-1,2,3-triazoles 1 yields, pressumably via the 4,5-diphenyl-1,2,3-triazolyl radical ( 2a ), 2,3-diphenyl-2H-azirine ( 11a ) and 2-aryl-4,5-diphenylimidazoles 14 as the major products. Upon irradiation 1-benzoylamino-4,5-diphenyl-1,2,3-triazole ( 1a ) gives 4,5-diphenyl-1 (2)H-1,2,3-triazole ( 4a ) via the 1,2,3-triazolyl radical 2a , together with benzamide ( 5a ) and 1,2-bisbenzoylhydrazine ( 6a ). Products 5a and 6a result from the benzoylamino radical 3a by hydrogen atom abstraction and dimerization respectively.     

Aza and deaza analogs of purine nucleosides (review)

Methods for the preparation of aza and deaza analogs of purine nucleosides, viz., nucleosides of imidazo[4,5-d]-v-triazines, imidazo[4,5-b]pyridines, and imidazo[4,5-c]pyridines, and their properties are described. References to the synthesis of nucleosides of imidazo[4,5-d]pyridazines, imidazo[4,5-c]pyridazines, and imidazo[4,5-b]pyrazines are also given.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 147–161, February, 1981.     

The synthesis of several imidazo[4,5-d]isothiazoles. Derivatives of a new ring system

Several derivatives of the new imidazo[4,5-d]isothiazole ring system have been synthesized from the appropriately substituted isothiazolediamines. The reaction of 3-methyl-4,5-diaminoisothiazole ( 4a ) with diethoxy-methyl acetate gave a low yield of 3-methylimidazo[4,5-d]isothiazole ( 5a ). However, the analogous reaction of 4,5-diaminoisothiazole ( 4b ) with diethoxymethyl acetate failed to yield the parent imidazo[4,5-d]isothiazole ring system. The diamines 4a and 4b were readily cyclized with thiocarbonyldiimidazole to give the unstable thiones 6a and 6b , which were alkylated in situ to afford good yields of the corresponding 5-methylthioimidazo[4,5-d]isothiazoles 7a and 7b , respectively. Neither of these compounds could be reduced to the corresponding 5-unsubstituted derivatives via treatment with Raney nickel. To the best of our knowledge, this is the first report of the imidazo[4,5-d]isothiazole ring system.     

Synthesis of alkyl (4,5-Dichloroisothiazol-3-yl) ketones and some of their derivatives

Reactions of 4,5-dichloroisothiazol-3-ylcarbonitrile with methylmagnesium iodide and ethylmagnesium bromide afforded the corresponding alkyl (4,5-dichloroisothiazol-3-yl) ketones. The reaction of (4,5-dichloroisothiazol-3-yl) methyl ketone with morpholine and piperidine provided 5-morpholino-(piperidino)-substituted derivatives, by the action of sodium borohydride in 2-propanol the keto group was reduced to alcoholic hydroxy group. The bromination of (4,5-dichloroisothiazol-3-yl) methyl ketone with elemental bromine gave bromomethyl (4,5-dichloroisothiazol-3-yl) ketone, whose reaction with thiourea resulted in 2-amino-4-(4,5-dichloroisothiazol-3-yl)thiazole.     

Synthesis of 4,5-decamethyleneimidazole, 4,5-decamethyleneoxazole, 4,5-decamethyleneisoxazole, 4,5-decamethyleneimidazolone-2, and 4,5-decamethylenepyrazole from cyclododecanone derivatives

4,5-Decamethyleneimidazole, 4,5-decamethyleneoxazole, and 4,5-decamethyleneimidazolone-2 were synthesized by reactions of 2-bromocyclododecanone and 2-hydroxycyclododecanone with formamide, ammonium formate, and urea, respectively. Condensation of 2-formylcyclododecanone with hydroxylamine and hydrazine hydrate resulted in 4,5-decamethyleneisoxazole, and 4,5-decamethylenepyrazole, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 891–893, May, 1994.     

Synthesis, Characterization, and Thermolysis of C(15)N(12)

Synthesis of 1-methyl-2-fluoro-4,5-dicyanoimidazole was done by halogen exchange between 1-methyl-2-bromo-4,5-dicyanoimidazole and potassium fluoride. Halogen exchange between 1-methyl-2-bromo-4,5-dicyanoimidazole and lithium chloride in N-methylpyrrolidinone at 150 degrees C yielded 1-methyl-2-chloro-4,5-dicyanoimidazole, and additional heating to 210 degrees C resulted in the demethylation to yield 2-chloro-4,5-dicyanoimidazole. Thermolyses of the 2-halo-4,5-dicyanoimidazole derivatives (F, Cl) and 1-iodo-2-halo-4,5-dicyanoimidazole derivatives (Cl, Br, I) between 100 and 290 degrees C were found to yield Tris(imidazo)[1,2-a:1,2-c:1,2-e]-1,3,5-triazine-2,3,5,6,8,9-hexacarbonitrile, or HTT, with (C(5)N(4))(3) composition. HTT has been characterized and purified and the crystal structure obtained. Thermolysis of HTT at 490-500 degrees C gives a material with C/N = 1.020. The thermal properties of HTT and its decomposition products show thermal stability to 350 degrees C.     

Reactions of derivatives of N-aryl-2-methyl-3-ethoxycarbonyl-4,5-dihydroxy-6-bromoindoles

Some 4,5-dihydroxyindoles, with an acetoacetic ester substituent at the 7 position were used to synthesize 7-acetonyl-4,5-dihydroxyindoles. Methylation of these compounds gave 4-hydroxy-5-methoxy- and 4,5-dimethoxyindoles. On reaction with hydroxylamine, these compounds were converted to the oximes. Oxidation of 4,5-dihydroxyindoles with nitric acid gave 4,5-indolequinones.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1054–1058, August, 1987.     

Reaction of 3-(alken-1-yl)-4,5-dihydro-3H-pyrazoles with sodium nitrite in acetic acid

3-Vinyl-4,5-dihydro-3H-pyrazole reacted with sodium nitrite in acetic acid to give 3-vinyl-1-nitroso-4,5-dihydro-1H-pyrazole, whereas 3-isopropenyl-4,5-dihydro-3H-pyrazole under analogous conditions was unexpectedly converted into a nitro derivative, 3-(1-methyl-2-nitrovinyl)-4,5-dihydro-1H-pyrazole.     

Nonstoichiometric,Protic Azolium Azolate Ionic Liquids Provide Unique Environments for N‐Donor Coordination Chemistry

Here we demonstrate that neat reactions of amphoteric azoles with more basic azoles give a family of finely tunable, nonstoichiometric liquids which are useful for N‐donor coordination chemistry. Reacting 4,5‐dicyanoimidazole (4,5‐DCNIm) with 1‐methylimidazole (1‐mim) gives new compounds with composition‐dependent speciation. Two crystalline compounds, a 1:1 protic salt, [H(1‐mim)][4,5‐DCNIm], and a 1:2 salt co‐crystal, [H(1‐mim)][4,5‐DCNIm]?4,5‐DCNIm, were isolated and structurally characterized, while differential scanning calorimetry revealed both suppression of crystallization and the presence of neutral and anionic species in the melt. Reactions of Cu(NO₃)₂?2.5 H₂O, CuO, and ZnO with the neat 2:1 1‐mim/4,5‐DCNIm melt resulted in the isolation of entirely N‐donor ligated complexes of the formula M(4,5‐DCNIm)₂(1‐mim)₄ (M=Cu, Zn).     

Oxidation of halohydroxybenzo-2,1,3-thiadiazoles with nitric acid

4,5-Dioxobenzo-2,1,3-thiadiazole has been synthesized. Its structure was proven by conversion to the known 4,5-dioximinobenzo-2,1,3-thiadiazole and to 2,1,3-thiadiazolo[4,5-a]phenazine, and by reduction to 4,5-dihydroxybenzo-2,1,3-thiadiazole. Oxidation of 5,6-dichloro-4,7-dihydroxy- and 5,7-dichloro-4-hydroxy-benzo-2,1,3-thiadiazoles forms 5,6-dichloro-4,7-dihydroxybenzo-2,1,3-thiadiazole, of known structure, and 7-chloro-4,5-dioxobenzo-2,1,3-thiadiazole; the latter by reaction with ortho-phenylene diamine is converted to 4-chloro-2,1,3-thiadiazolo[4,5-a]phenazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 850–852, June, 1987.     

Retro-ene reaction. II. Reaction of 4,5-dichloro-1-hydroxy-methylpyridazin-6-one with alkyl halides and carboxylic acid chlorides

1-Alkyl-4,5-dichloropyridazin-6-oncs and (4,5-dichloro-6-oxopyridazin-1-yl)methylcarboxylates were synthesized from 4,5-dichloro-1-hydroxymethylpyridazin-6-one and the corresponding alkyl halides or carboxylic acid chlorides. Also the reaction mechanisms via a fragmentation of retro-ene type are discussed.     

Syntheses of five potential heterocyclic amine food mutagens

The syntheses of the potential heterocyclic amine food mutagens, 3,5,7-trimethyl-2-aminoimidazo-[4,5-b]pyridine, 1,4,7-trimethyl-2-aminoimidazo[4,5-c]pyridine, 1,6,7-trimethyl-2-aminoimidazo[4,5-c]-pyridine, 3,4,6-trimethyl-2-aminoimidazo[4,5-c]pyridine, and 1,4,6-trimethyl-7-aminoimidazo[4,5-c]-pyridine are described.