Photorearrangement of spiro-oxaziridines - applications in the syntheses of hexahydro-5H-pyrrolo-[2]benzazepin-5-ones and a tetrahydro-1H,5H-pyrroloisoquinolin-5-one

Regiospecific photorearrangements of spiro-oxaziridines derived from 2-methylindan-1-one, 2-methyltetral-1-one and 1-methyltetral-2-one afforded the title compounds.     

Alkaloids of Glycosmis arborea—II Structure of arborine

On the basis of a critical study of the ultra-violet and the infra-red absorption spectra of arborine, dihydroarborine, 1,2-dimethylquinazol-4-one, 2-ethyl-1-methylquinazol-4-one, 2,3-dihydro-1,2-dimethylquinazol-4-one and 2,3-dihydro-2-ethyl-1-methylquinazol-4-one, it has been shown that arborine is 2-benzyl-1-methylquinazol-4-one and not the tautomeric form, 2-benzylidene-1-methylquinazol-4-one. This has been confirmed on the basis of the nuclear magnetic resonance spectrum of arborine. Incidentally, it has been shown that 'glycosine' of Chatterjee and Ghosh Majumdar is not a new alkaloid and this name should be deleted from the literature.     

Synthesis Of 1-Benzazepines as Precursors of 1-Benzazepinediones

The synthesis of 6-hydroxy-7-nitro-1-benzazepine-2-one 7 from 5-hydroxy-1-tetralone 1 and 6-hydroxy-1-benzazepine-2-one 2 is described. Bromination of 6-hydroxy-1-benzazepine-2-one 2 with NBS in ethyl acetate afforded 7-bromo-6-hydroxy-1-benzazepine-2-one 13 and 7,9-dibromo-6-hydroxy-1-benzazepine-2-one 14. Oxidation of benzazepinone 13 with (diacetoxyiodo)benzene provided 7-bromo-1-benzazepine-2,6,9-trione 5.     

Nitrogen configuration determined by X-ray analysis on an homogeneous series of 3-Indolinones

The X-ray diffraction analyses of 2-methyl-2-phenylindolin-3-one 1 , 1,2-dimethyl-2-phenylindolin-3-one 2 , 1-hydroxy-2-methyl-2-phenylindolin-3-one 3 and 1-methoxy-2-methyl-2-phenylindolin-3-one 4 have been carried out and the structural data were compared with those of 1-oxyl-2-methyl-2-phenylindolin-3-one 5 . The results demonstrate that only compounds 2 and 5 show planar trigonal geometry which is coplanar with the conjugated benzene ring of the indolinic nucleus, whereas compounds 3 and 4 show a marked pyramidality of the nitrogen. Even if compound 1 shows a certain pyramidality of the nitrogen, it has been considered similar to compound 2 . The reactivity of all studied compounds fit the structural data.     

Chiral phosphorus ligands for the asymmetric conjugate addition of organocopper reagents

The asymmetric conjugate addition of medium order alkyl cuprate reagents. R₅Cu₃Li₂, to 2-cyclohexen-1-one. 2-cyclopenten-1-one and 2-cyctohepten-1-one, with the help of phosphorus ligand B^*, is described. 3-Alkyl substituted cyclohexanones are obtained in essentially optically pure form. The same chiral ligand, associated with CuI, in catalylic amount (10%), allows the asymmetric conjugate addition of Et₂Zn to 2-cyclohexen-1-one.     

Identification of impurities affecting commercial ethylene glycol UV transmittance

As a raw material for making polyesters, ethylene glycol has a special specification of UV transmittance. At present, ethylene glycol produced by some plants still has low UV transmittance rendering it unsuitable for use in polyester production. In this paper, a method was developed for the identification of the impurities that cause commercial ethylene glycol to have low UV transmittance, using solid-phase extraction (SPE) and some analytical techniques such as high-performance liquid chromatography, gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectroscopy. The major UV-absorbing impurities were identified as some alkyl homologues of 2-hydroxycyclopent-2-en-1-one, including 2-hydroxy-3,5-dimethylcyclopent-2-en-1-one, 2-hydroxy-3-methylcyclopent-2-en-1-one, 2-hydroxy-3,4-dimethylcyclopent-2-en-1-one, 2-hydroxy-3-ethyl-4-methylcyclopent-2-en-1-one and 2-hydroxy-3-ethylcyclopent-2-en-1-one. Their concentrations were estimated to be less than 2 microg ml(-1). It is believed that with the above results, ethylene glycol-producing plants might make process improvements to remove these impurities more effectively and more easily.     

Simple and regioselective bromination of 5,6-disubstituted-indan-1-ones with Br2 under acidic and basic conditions

Bromination of 5,6-dimethoxyindan-1-one with Br(2) in acetic acid at room temperature produced exclusively the corresponding 2,4-dibromo compound in 95% yield. Reaction of 5,6-dimethoxyindan-1-one with Br(2) in the presence of KOH, K(2)CO(3) or Cs(2)CO(3 )at ~0 degrees C( )gave the monobrominated product 4-bromo-5,6-dimethoxyindan-3-one in 79%, 81% and 67% yield, respectively. 5,6-Dihydroxyindan-1-one was dibrominated on the aromatic ring affording 4,7-dibromo-5,6-dihydroxyindan-1-one both in acetic acid at room temperature and in the presence of KOH at ~0 degrees C. 5,6-Difluoroindan-1-one and 1-indanone were alpha-monobrominated in acetic acid and alpha,alpha-dibrominated under KOH conditions at room temperature.     

Microwave-assisted synthesis and antibacterial activity of some pyrazol-1-ylquinoxalin- 2(1H)-one derivatives

3-Hydrazinoquinoxalin-2(1H)-one was prepared from quinoxaline-2,3-dione and subsequently used for the synthesis of some potentially biologically active 3-(pyrazol-1-yl)quinoxalin-2(1H)-one derivatives. While 3-(3,5-dimethylpyrazol-1-yl)quinoxalin-2(1H)-one showed a comparative effect with streptomycin, 3-(5-oxo-3-phenyl-4,5-di- hydropyrazol-1-yl)quinoxalin-2(1H)-one was found to be the most active with an MIC value of 7.8 μg/ml.     

Benzofused tricycles based on 2-quinoxalinol

This paper describes our recent efforts to synthesize novel compound scaffolds integrating 2-quinoxalinol with privileged structures of 1,3-dihydro-benzoimidazol-2-one, 1,3-dihydro-benzoimidazole-2-thione, 3-hydroxy-1H-quinoxalin-2-one, 2H-benzo[1,4]oxazin-3-ol, 2H-benzo[1,4]thiazin-3-ol, and 1,3,4,5-tetrahydro-benzo[1,4]diazepin-2-one, respectively. Eight novel benzofused tricycles and their substituent diversity points were developed. These include pyrazino[2,3-g]quinoxaline-2,8-diol (I), 3-hydroxy-6,8,9,10-tetrahydro-1,4,6,10-tetraaza-cyclohepta[b]naphthalen-7-one (II), 6-hydroxy-4H-1-oxa-4,5,8-triaza-anthracen-3-one (III), 6-hydroxy-4H-1-thia-4,5,8-triaza-anthracen-3-one (IV), 6-hydroxy-1,1-dioxo-1,4-dihydro-2H-1lambda(6)-thia-4,5,8-triaza-anthracen-3-one (V), 6-hydroxy-1,3-dihydro-imidazo[4,5-g]quinoxalin-2-one (VI), 6-hydroxy-1,3-dihydro-imidazo[4,5-g]quinoxaline-2-thione (VII), and 7-hydroxy-1,4-dihydro-pyrazino[2,3-g]quinoxaline-2,3-dione (VIII). This strategy of integrating two benzofused privileged structures into one molecule may provide a greater chance for the discovery of novel lead compounds.     

Regiocontrolled syntheses of some new spiro[polycyclic-1′-isothiochroman]-4′-one derivatives

Indan-1-one (1a), 1-tetralone (1b), fluorenone (1c), and anthrone (1d) reacted with mercaptoacetic acid in toluene in the presence of p-toluenesulfonic acid to give spiro[indan-1,2′-[1′,3′]oxathialan]-5′-one (2a), spiro[tetrahydro-naphthalene-1,2′-[1,3′]oxathialan]-5′-one (2b), spiro[fluorene9,2′-[1′,3′]-oxathialan]-5′-one (2c), and spiro[anthracene-9(10H)-2′-[1′,3′]-oxathialan]-5′-one (2d), respectively. Compounds 2a–d reacted with arenes in the presence of aluminum chloride to yield spiro[polycyclic-1′-isothiochroman]-4′-one derivatives 3a–t. The mechanisms of these reactions are discussed. All the synthesized spiroheterocycle derivatives were identified by conventional methods (IR, ¹H-NMR spectroscopy) and elemental analyses. © 1996 John Wiley & Sons, Inc.     

Facile Regioselective Synthesis of Pyrano[3,2-c][1]benzo-thiapyran-5(2H)-one and 2-Methyl Furo[3,2-c][1] Benzothiapyran-4-one

The hitherto unreported title compounds were obtained in good yields by the application of [3,3]sigmatropic rearrangement on 4-]2′-propynyloxy] [1]benzothiapyran-2-one and 4-[2′-propenyloxy][1]benzothiapyran-2-one or 4-[2′-chloro-2′-propenyloxy][1]benzothiapyran-2-one respectively.     

The Clemmensen Reduction of α, β-Unsaturated Ketones

Eleven structurally different α, β-unsaturated ketones were subjected to the Clemmensen reduction under anhydrous conditions using amalgamated zinc, hydrogen chloride in a solution of ethyl ether, and acetic anhydride. In all cases but one the formation of cyclopropyl acetates was observed. 4-Methyl-3-penten-2-one, methyl vinyl ketone, 2-isopropylidene-1-cyclopentanone, and 2-cyclohepten-1-one led to substituted cyclopropyl acetates. Stereospecific reactions were found with 2-ethylidene-1-cyclopentanone, 2-benzylidene-1-cyclohexanone, and methyl 1-cyclohexenyl ketone, whereas 3-penten-2-one, 3-methyl-3-buten-2-one, and 2-methyl-2-cyclohexen-1-one afforded mixtures of the isomeric cyclopropyl acetates. These results are interpreted in terms of the intital formation of an allylic anion which undergoes electrocyclic closure. A stereospecific course is followed when geometric constraints permitted. Exceptions are discussed.     

Synthesis of the dibenzo[f,h]phthalazine and dibenzo[f,h]cinnoline skeleton via a ‘Suzuki-Pd-catalyzed intramolecular arylation’ and a ‘Suzuki-Pschorr’ approach

Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2H)-one yielded hitherto unknown 2-benzyldibenzo[f,h]phthalazin-1(2H)-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl)-4-phenylpyridazin-3(2H)-one via a Pschorr type reaction was also investigated. Similarly, the construction of 2-methyldibenzo[f,h]cinnolin-3(2H)-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(2H)-one and 2-methyl-5-(2-aminophenyl)-6-phenylpyridazin-3(2H)-one is also reported. Removal of the N-benzyl protective group of 2-benzyl-dibenzo[f,h]phthalazin-1(2H)-one with AlCl₃ yielded unsubstituted dibenzo[f,h]phthalazin-1(2H)-one.     

Lewis base effects in the Baylis-Hillman reaction of imines with cyclohex-2-en-1-one and cyclopent-2-en-1-one

In the Baylis-Hillman reaction of N-benzylidene-4-methyl-benzenesulfonamide with cyclohex-2-en-1-one or cyclopent-2-en-1-one, we found that, in the presence of a catalytic amount of DMAP, the Baylis-Hillman reaction can be greatly accelerated to give the normal Baylis-Hillman adduct 1 or 3 in good or very high yields: moreover, using PBu3 as a Lewis base in the reaction of N-benzylidene-4-methylbenzenesulfonamide with cyclopent-2-en-1-one, the normal Baylis-Hillman adducts 3 could be obtained in very high yields within 5 h, however, using PBu3 or DBU as a Lewis base in the reaction of N-benzylidene-4-methyl-benzenesulfonamide with cyclohex-2-en-1-one, beside the normal Baylis-Hillman adduct 1 abnormal Baylis-Hillman adduct 3-aryl-2-[(4-methylphenyl)sulfonyl]-2-azabicyclo[2.2.2]octan-5-one 2 was formed at the same time; the substituent's effects were also examined.     

Isolierung und Struktur von langkettigen Alkylphenolen und -pyrocatecholen aus Plectranthus albidus (Labiatae)

Isolation and Structure of Long-Chain Alkylphenols and -catechols from Plectranthus albidus (Labiatae) From the title plant, a series of even-numbered long-chain, phenol- or pyrocatechol-derived 1-arylalkan-5-ones was isolated by classical chromatography and preparative reversed phase HPLC. By chemical and spectroscopic methods, including coupled chromatographic techniques (GC/MS/FT-IR, HPLC/MS), their structures were established to be 1-(4′-hydroxyphenyl)tetradecan-5-one ( 2a ), 1-(4′-hydroxyphenyl)hexadecan-5-one ( 2b ), 1-(4′-hydroxyphenyl)octadecan-5-one ( 2c ), and (Z)-1-(4′-hydroxyphenyl)octadec-13-en-5-one ( 2d ); (E,E)-1-(3′,4′-dihydroxyphenyl)deca-1,3-dien-5-one ( 1a ), 1-(3′,4′-dihydroxyphenyl)dodecan-5-one ( 3a ), 1-(3′,4′-dihydroxyphenyl)-tetradecan-5-one ( 3b ), 1-(3′,4′-dihydroxyphenyl)hexadecan-5-one ( 3c ), 1-(3′,4′-dihydroxyphenyl)octadecan-5-one ( 3d ), 1-(3′,4′-dihydroxyphenyl)icosan-5-one ( 3e ), and (Z)-1-(3′,4′-dihydroxyphenyl)octadec-13-en-5-one ( 3f ). In vitro, the compounds show significant antioxidant activity, the inhibitory concentration of the most potent one, 1a , being slightly lower than for 2-(tert-butyl)-4-methoxyphenol (BHA) and 2,6-di(tert-butyl)-4-methylphenol (BHT) in the Fe²⁺-catalysed autooxidation of linoleic acid, whereas the acitivities of phenols 2a–d are in the same order of magnitude as α-tocopherol.     

OAP-H2O2-HRP酶促反应产物与DNA相互作用的光谱及电化学研究

脱氧核糖核酸(DNA)是生物的基本遗传物质，对其研究是生命科学研究领域中极其重要的内容，其中有关DNA靶向分子与DNA之间相互作用的研究一直是一个比较活跃的领域，继Bard等用电化学方法对溶液中的电活性物质与DNA相互作用进行研究之后，又有许多相关的研究成果相继报道。3-氨基酚噁嗪(AP，即寻霉素A)与放线菌素D的生成有关，放线菌素D在伴随DNA指导RNA的合成中起作用，AP被用作放线菌素D的行为模型，对放线菌素D还原成1个N-10中心阴离子提供信息。     

(5R,6R)-6-苯基-5-(苯磺酰基乙酰基)二环[2.2.1]-2-庚烯的合成及结构表征

报道了一种制备4-苯基-1-苯磺酰基-3-丁烯-2-酮的新合成方法. 4-苯基-3-丁烯-2-酮与溴化试剂Ph₃P^＋CH₂CH₂- COOHBr 作用, 得到1-溴-4-苯基-3-丁烯-2-酮, 不经分离直接与苯亚磺酸钠发生亲核取代反应, 得到4-苯基-1-苯磺酰基-3-丁烯-2-酮. 将此反应产物作为亲双烯体与环戊二烯在手性钛金属催化剂催化下进行不对称Diels-Alder反应, 得到了＞99% ee 的环加成产物(5R,6R)-6-苯基-5-(苯磺酰基乙酰基)二环[2.2.1]-2-庚烯. 用X衍射法对产物的晶体结构进行了测定, 讨论了反应机理, 通过元素分析, NMR, MS对产物的结构进行了表征.     

Five new peltogynoids from underground parts of Iris bungei: a Mongolian medicinal plant

Five new peltogynoids, irisoids A-E (1-5), have been isolated from the underground parts of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods and were found to be 1,8,10-trihydroxy-9-methoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (1), 1,8-dihydroxy-9,10-dimethoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (2), 1,10-dihydroxy-8,9-dimethoxy-[1]benzopyrano-13,2-c][2]-benzopyran-7(5H)-one (3), 1,8-dihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (4), and 1,8,11-trihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (5). The structure of irisoid B (2) was established unambiguously by X-ray diffraction study.     

Tautomerism-dependent ring construction of N-heterocyclic compounds from the reactions of 1-alkynyl Fischer carbene complexes and substituted pyrazolinones

Four types of N-heterocyclic ring systems were successfully constructed from the reactions of 1-alkynyl Fischer carbene complexes (OC)5M=C(OEt)C[triple bond]CPh (1) (M = Cr, W) and substituted pyrazolinones (2). Reactions of 1 with 3-methyl-2-pyrazolin-5-one (2a), 3-n-propyl-2-pyrazolin-5-one (2b), 3,4-dimethyl-2-pyrazolin-5-one (2c), 3,4-trimethylene-2-pyrazolin-5-one (2d), or 3,4-tetramethylene-2-pyrazolin-5-one (2e) generated three kinds of Fischer aminocarbene complexes (3-5), and reactions of 1 with phenyl-substituted pyrazolinones, i.e., 3-phenyl-2-pyrazolin-5-one (2f) and its tautomer 3-phenyl-3-pyrazolin-5-one (2g), gave Fischer alkoxycarbene complexes (6) as the major products and aminocarbene complexes of types 3-5 as the minor products. Multiple tautomerism of pyrazolinones is attributed to the versatile formation of N-heterocyclic Fischer carbene complexes. Oxidative demetalation of complexes 3-6 with pyridine N-oxide or m-chloroperoxybenzoic acid efficiently afforded organic carbonyl products, and thus, strongly fluorescent syn-mixed-bimanes were prepared. The present findings constitute an alternative new method to synthesize mixed bimanes and other novel N-heterocyclic compounds.     

Photochemical reactivity of α,β-unsaturated δ-lactams: Synthesis of seco-steroids. Photochemical reactions. XIII [1]

The UV. irradiation of 17 β-hydroxy-2-aza-4-androsten-3-one (1) , N-methyl-17 β-hydroxy-2-aza-4-androsten-3-one (3) , 17 β-hydroxy-4-aza-5 β-androst-1-en-3-one (2) and N-methyl-17 β-hydroxy-4-aza-5 β-androst-1-en-3-one (4) , gives rise to 1,10-seco (from 1 and 3 ) and 5, 10-seco (from 2 and 4 ) steroids.