Synthesis of 6-Aroyl-3,3,5,5-tetramethyl-2,3,5,6-tetrahydropyran-2,4-diones and Their Reaction with Phenylhydrazine

Methyl 4-bromo-3-oxo-2,2,4-trimethylpentanoate reacts with zinc and arylglyoxals yielding 6-aroyl-3,3,5,5-tetramethyl-2,3,5,6-tetrahydropyran-2,4-diones. The latter with phenylhydrazine afford 6-(1-aryl-2-phenylhydrazonomethyl)-3,3,5,5-tetramethyl-2,3,5,6-tetrahydropyran-2,4-diones.     

Conversion of 2-ethyl-3,3,5,5-tetramethyl- and 2-ethyl-1,3,3,5,5-pentamethyl-1,2,4,5-tetra-hydro-3h-benz-2-azepines by the action of ethyl propiolate

It has been shown that, on interacting 2-ethyl-3,3,5,5-tetramethyl- and 2-ethyl-1,3,3,5,5-pentamethyl-1,2,4,5-tetrahydro-3H-benz-2-azepines with ethyl propiolate in methanol, fission of the azepine ring occurs at the C(1)–N(2) bond involving a molecule of solvent. The indicated azepines do not react with acetylenedicarboxylic acid ester under these conditions.     

Preparation and nitrosation of 3,4-dimethyl-3-penten-2-one (e)- and (z)-oximes. Formation of 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide and of 2-isoxazoline derivatives

The stereoisomeric (E)- and (Z)-oximes of 3,4-dimethyl-3-penten-2-one were prepared and nitrosated with butyl nitrite in methanol. The (E)-oxime gave 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide in nearly quantitative yield, while the (Z)-oxime reacted less readily, giving a lower yield of the same product, with five other products identified as isoxazoline derivatives. Three of these were 4-hydroxy-, 4-methoxy-, and 4-nitro-3,4,5,5-tetramethyl-2-isoxazoline. The fourth was the O-(3,4,5,5-tetramethyl-2-isoxazolin-4-yl) derivative of the starting (Z)-oxime, and the fifth was 4-methylene-3,5,5-trimethyl-2-isoxazoline.     

Hypervalent iodine oxidation. Synthesis of spin labeled, 1-oxyl-2,2,6,6-tetramethylpiperidine derivatives

Oxidation of 1-oxyl-2,2,6,6-tetramethyl-4-piperidone ( 1 ) with [I,I-bis(acetoxy)iodo]benzene in methanolic potassium hydroxide yields 1-oxyl-4,4-dimethoxy-3-hydroxy-2,2,6,6-tetramethylpiperidine ( 2 ). Treatment of 2,2,6,6-tetramethyl-4-piperidone ( 3 ) with [I,I-bis(acetoxy)iodo]benzene in methanolic potassium hydroxide gave 3-methoxy-2,2,6,6-tetramethyl-4-piperidone ( 4 ) which on oxidation with 30% hydrogen peroxide and catalytic amount of sodium tungstate gave 1-oxyl-3-methoxy-2,2,6,6-tetramethyl-4-piperidone ( 5 ). The esr spectra of 1-oxyl-4,4-dimethoxy-3-hydroxy-2,2,6,6-tetramethylpiperidine ( 2 ) as well as 1-oxyl-3-methoxy-2,2,6,6-tetramethyl-4-piperidone ( 5 ) show three lines.     

Conversion of 3,4-Dihyoro-2H-Pyrrole-I Oxide to 2H-Pyrrole Using Chlorosulfonyl Isocyamate

3,4-Dihydro-2H-pyrrole-l-oxides la-e react with Chlorosulfonyl isocyanate (CSI), to give the 2H-pyrroles 2a-e. 3,4-Dihydro-2,2,4,4-tetramethyl-2H-pyrrole-1-oxide If on treatment with CSI furnished 3,3,5,5-tetramethyl pyrrolidin-2-one.     

Photoaddition of water and methanol to 2,2,4,6-tetramethyl-1,2-dihydroquinoline

Products of the steady-state photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline (1) in water, methanol, and water—ethanol were isolated for the first time and identified by¹H and¹³C NMR spectroscopy, IR spectroscopy, and mass spectrometry. As a result of the photolysis, the molecule of the solvent is added to the double bond of the heterocycle with formation of 4-hydroxy- (2) or 4-methoxy-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline (3) in water and methanol, respectively. Compounds2 and3 are converted gradually into1 in the dark. The rate of the back reaction depends on the solvent and the concentration of the product. Comparison of the products of the photolysis in methanol and hexane at 45 °C and of the azoisobutyronitrile-initiated oxidation of1 at the same temperature has shown that unlike the photolysis in hexane, aminyl radicals are not precursors of the product of the photolysis in methanol. The reaction proceedsvia an excited singlet state. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2072–2077, November, 1999.     

THE PHOTOREACTIONS AND FREE RADICAL INDUCED REACTIONS OF 1,3-DIMETHYLURACIL IN METHANOL AND OTHER ALCOHOLS

Abstract— Photoexcited 1,3-dimethyluracil (DMU) reacts with methanol to give 1,3-dimethyl-6-hydroxymethyl-5-hydrouracil ( 1 a) in addition to cyclobutane type dimers and 1,3-dimethyl-6-methoxy-5-hydrouracil ( 2 a). Free radical induced reaction, initiated by photodecomposition of di- t -butyl peroxide with light of wavelength greater than 290nm, leads to 1 a, 5,6-dihydroxymethyl-5,6-dihydro-1,3-dimethyl-uracil ( 1 d) and 6-hydroxymethyl-1,3-dimethyluracil as the products.     

Characterization of titanium dioxide photoactivity following the formation of radicals by EPR spectroscopy

In order to find ways to characterize oxygen-saturated aqueous TiO₂ suspensions, the formation of photo-induced free radicals was followed by EPR spectroscopy, using as indicators N-oxide and nitrone spin trapping agents, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline N-oxide (TMPO), α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POB N), 4-(N-methylpyridyl)-N-tert-butylnitrone (MePyBN), as well as semi-stable free radicals, 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl (TEMPOL), cation radical of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), diammonium salt (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH). DMPO and TMPO are efficiently oxidized to the EPR-silent products via radical in termediates. Conversely, the nitrone spin traps (POBN and MePyBN) showed selective formation of hydroxyl radical spin adducts upon continuous irradiation of oxygenated TiO₂ suspensions. Their concentrations increased proportionally with the amount of photocatalyst and irradiation time. The EPR spectrum of the semi-stable free radicals TEMPOL, ABTS^·+ or DPPH is gradually eliminated during irradiation, and this system represents a simple technique for the evaluation of TiO₂ activity.     

Methanol addition to dihapto-coordinated rhenium complexes of furan

The complexes [TpRe(CO)(L)(4,5-eta(2)-furan)], present as diastereomeric mixtures (L = (t)BuNC (1A, 1B), PMe(3) (2A, 2B), pyridine (3A, 3B), or 1-methylimidazole (4A, 4B)), undergo acid-catalyzed methanol addition in CH(2)Cl(2) at -40 degrees C, resulting in the syntheses of dihapto-coordinated 2-methoxy-2,3-dihydrofuran complexes. In all cases, two diastereomers resulted, one in which the oxygen of the dihydrofuran is oriented toward the L ligand (5A, 6A, 7A, and 8A), and one in which the oxygen is oriented away from the L ligand (5B, 6B, 7B, and 8B). In all cases, the methoxy group adds stereoselectively, anti to the metal fragment. In addition, the (t)BuNC complex 1 yields a dihapto-coordinated vinyl ether (5C) that results from ring opening of the protonated furan ligand. In no case does the diastereomeric ratio of products correlate with that of the starting material.     

Reaction modes and mechanism in indolizine photooxygenation reactions

Photooxygenations of 1,2-, 1,3-, and 2,3-di- and 1,2,3-trisubstituted indolizines 1a-1f under different reaction conditions in methanol and acetonitrile have been investigated to establish the general reaction pattern and mechanism in indolizine photooxygenation in view of the influence of the ring substituents and substitution pattern. Photooxygenations of 1-acyl-2-phenylindolizines 1a and 1b and 1,3-dibenzoyl-2-phenylindolizine (1d) are self-sensitized, while those of 1-(p-nitrobenzoyl)-2-phenylindolizine (1c) and 2-phenyl-3-(p-chlorobenzoyl)indolizine (1e) need to be sensitized by rose bengal (RB) or methylene blue (MB). These reactions proceed via a singlet oxygen mechanism yet follow different pathways in methanol and in acetonitrile, with peroxidic zwitterion D (in methanol) and dioxetane E across the indolizine C2-C3 bond (in acetonitrile) as the intervening intermediates. Methanol trapping of the peroxidic zwitterion results in C3-N bond cleavage and pyrrole ring opening to give the corresponding (E)- and (Z)-3-(2-pyridinyl)-3-benzoylpropenoic acid methyl esters (2 and 3) and 4-(2-pyridinyl)-3-phenyl-5-aryl-5-hydroxyfuran-2-one (4) as products in methanol, while O-O bond homolysis of the dioxetane furnishes 3-(2-pyridinyl)-3-benzoyl-2-phenyloxirane-2-carboxaldehyde (6) and 1-(6-methyl-2-pyridinyl)-2-phenylethanedione (5) as products in acetonitrile. 3-Benzoyl-1-indolizinecarboxylic acid methyl ester (1f) is unreactive toward singlet oxygen; however, it could be photooxygenated under electron transfer conditions with 9,10-dicyanoanthracene (DCA) as a sensitizer. This reaction takes place by the combination of the indolizine cation radical with the superoxide anion radical (or molecular oxygen) to give the pyridine ring oxidized methyl 3-benzoyl-5-methoxy-8-hydroxy-1-indolizinecarboxylate (9f), dimethyl 2-(2-pyridinyl)fumarate (8f), and dimethyl 2-(2-pyridinyl)maleate (7f) as products.     

Analytical chemistry of synthetic routes to psychoactive tryptamines. Part I. Characterisation of the Speeter and Anthony synthetic route to 5-methoxy-N,N-diisopropyltryptamine using ESI-MS-MS and ESI-TOF-MS

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT), a new psychoactive tryptamine derivative, has been synthesised by the Speeter and Anthony procedure. This synthetic route was characterised by ESI-MS-MS, ESI-TOF-MS and NMR. Side products have been identified as 3-(2-N,N-diisopropylamino-ethyl)-1H-indol-5-ol (5), 2-N,N-diisopropylamino-1-(5-methoxy-1H-indol-3-yl)-ethanol (6), 2-(5-methoxy-1H-indol-3-yl)-ethanol (7) and 2-N,N-diisopropylamino-1-(5-methoxy-1H-indol-3-yl)-ethanone (8).     

SYNTHESIS OF NOVEL BI-FUNCTIONAL COPOLYMER BEARING STERICALLY HINDERED PHENOL AND HINDERED AMINE GROUPS VIA RING-OPENING METATHESIS POLYMERIZATION

Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized by RuCl_2(=CHPh)(PCy_3)_2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol(SHP)and hindered amine(HLAS)groups via ring-opening metathesis polymerization(ROMP).The resulting copolymers were characterized by gel permeation chromatography(GPC),~1H-NMR and diffe...     

Interaction of a lithiated nitronyl nitroxide with polyfluorinated 1,4-naphthoquinones

A 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl lithium derivative was found to react with 2-methoxypentafluoro-1,4-naphthoquinone to form a product of addition at the carbonyl function: radical 2-(3,5,6,7,8-pentafluoro-1-hydroxy-2-methoxy-4-oxo-1,4-dihydronaphthalen-1-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl. The yield of the addition product increased with temperature and reached 84% at 0?°C. The reaction of the lithium derivative with hexafluoro-1,4-naphthoquinone gave rise to a product of addition at both carbonyl groups, namely, nitronyl nitroxide diradical 2,3,5,6,7,8-hexafluoro-1,4-bis(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1H-imidazole-2-yl)-1,4-dihydronaphthalene-1,4-diol in a 16% yield. The structures of both mono- and diradical were solved by X-ray diffraction analysis, which revealed formation of an intramolecular H-bond between the OH group and nitroxide oxygen. According to electron paramagnetic resonance (EPR) spectroscopy, the obtained mono- and dinitroxide are prone to spontaneous deoxygenation in a toluene solution to give corresponding iminonitroxides. In water, they are much more stable.     

Study of the reaction products of flavonols with 2,2-diphenyl-1-picrylhydrazyl using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry

The products obtained after the reaction between flavonols and the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) in both methanol and acetonitrile were characterized using liquid chromatography coupled with negative electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) and NMR spectroscopy. The flavonols studied were quercetin, kaempferol and myricetin. In methanol, two reaction products of oxidized quercetin were identified using LC/ESI-MS/MS and NMR. Quercetin was oxidized through a transfer of two H-atoms to DPPH(*) and subsequently incorporated either two CH(3)OH molecules or one CH(3)OH- and one H(2)O molecule giving the products 2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-2,3-dimethoxy-2,3-dihydrochromen-4-one and 2-(3,4-dihydroxyphenyl)-3,3,5,7-tetrahydroxy-2-methoxy-2,3-dihydrochromen-4-one, respectively. LC/ESI-MS/MS analysis revealed that in methanol, kaempferol and myricetin also gave rise to methoxylated oxidation products similar to that identified for quercetin. Kaempferol, in addition, also exhibited products where a kaempferol radical, obtained by a transfer of one H-atom to DPPH(*), reacted with CH(3)OH through the addition of CH(3)O(*), yielding two isomeric products. When the reaction took place in acetonitrile, LC/ESI-MS/MS analysis showed that both quercetin and myricetin formed stable isomeric quinone products obtained by a transfer of two H-atoms to DPPH(*). In contrast, kaempferol formed two isomeric products where a kaempferol radical reacted with H(2)O through the addition of OH(*), i.e. similar to the reaction of kaempferol radicals with CH(3)OH.     

The effect of alkali and Ce(III) ions on the response properties of benzoxazine supramolecules prepared via molecular assembly

A series of benzoxazine monomer supramolecules with different substituted groups on their benzene ring was prepared with a Mannich reaction and characterized by FTIR, 1H-NMR and MS. The obtained products were 3,4-dihydro-3-(2'-hydroxyethylene)-6-methyl-2H-benzoxazine (BM1), 3,4-dihydro-3-(2'-hydroxyethylene)-6-ethyl-2H-benz-oxazine (BM2), and 3,4-dihydro-3-(2'-hydroxyethylene)-6-methoxy-2H-benzoxazine (BM3). The efficiency of alkali metal ion extraction from the products was determined with Pedersen's technique, while the complexation of the Ce(III) ion was confirmed by the Job's and the mole ratio methods. The evidence of complex formation between benzoxazine monomers and Ce(III) ions was obtained with FTIR and a computational simulation. Single phase ceria (CeO?) as observed with XRD was successfully prepared by calcinating the Ce(III)-benzoxazine monomer complexes at 600 °C for 2 h. In addition, the geometry of the ceria nanoparticles confirmed by TEM is spherical, with an average diameter of 10-20 nm.     

若干D环带硝基的小檗因衍生物的光环化合成

通过酰烯胺的光环化反应, 合成了六个D环带硝基的小檗因类化合物。在酰烯胺的制备中, 还得到了几个非预期的副产物, 阐明了它们的结构。     

Synthesis of Tri- and Disalicylaldehydes and Their Chiral Schiff Base Compounds

A suitable procedure for convenient preparation of 1,3,5-tris(4-hydroxy-5-formylphenyl)benzene (6) was exploited via 5-bromosalicylaldehyde as starting reactant. Among the obtained products, compound 6, 4-methoxy-3-formylphenylboronic acid (9), 1,3,5-tris(4-methoxy-5-formylphenyl)benzene (10), and 4-methoxy-4′-hydroxyl-3,3′-diformyl-1,1′-diphenyl (11) had not been reported previously. Two new chiral Schiff base ligands, L1 and L2, were obtained from the tri- or disalicylaldehydes.     

由4-甲氧基-2-溴代丁烯内酯合成螺环-环丙烷类化合物的研究

以4-甲氧基-2-溴代丁烯内酯为合成子,在温和条件下与不同的亲核试剂通过串联的双Michael加成及分子内的亲核取代反应,得到螺环-环丙烷类化合物8a～8d.通过元素分析,IR,¹HNMR,¹³CNMR和MS对化合物进行了结构表征,其中化合物8d经单晶X射线衍射测定,确定了其立体化学结构.     

Triterpene and coumarins from Skimmia laureola

In the course of our studies on the chemical constituents of the leaves of Skimmia laureola, a new triterpene O-methyl cyclolaudenol (1) and a new coumarin, (+)-7-methoxy-6-(2'R-methoxy-3'-hydroxy-3'-methyl butyl) coumarin (2) were isolated. In addition five known coumarins, isogospherol (3), heraclenol (4), 5,8-dimethoxy coumarin-2H-1-benzopyran-2-one (5), 7-methoxy-6[2'-oxo-3'-methyl butyl] coumarin (6), and (+)-ulopterol (7) were also isolated for the first time from this plant. The structures were identified by spectroscopic studies and the stereochemistry at C-2' in compounds 3 and 4 were established by Horeau's procedure.     

Anodic cyanation of 1-methylpyrazole

The electrooxidation of 1-methylpyrazole in methanol containing sodium cyanide produced 1-methyl-pyrazole-4-carbonitrile 2 and ?5-carbonitrile 3 in yields of 23 and 8%, respectively (2e-oxidation products), together with 4-methoxy-1-methylpyrazole-5-carbonitrile 4 (4e-oxidation product, 4%).