- Synthesis of new Zn (II) complexes for photo decomposition of organic dye pollutants, industrial wastewater and photo-oxidation of methyl arenes under visible-light
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Synthesis of new Schiff's base Zn-complexes for photo-oxidation of methyl arenes and xylenes are reported under visible light irradiation conditions. All the synthesized new ligands and Zn-complexes are thoroughly characterized with various spectral analyses and confirmed as 1:1 ratio of Zn and ligand with distorted octahedral structure. The bandgap energies of the ligands are higher than its Zn-complexes. These synthesized new Zn(II) complexes are used for the photo-fragmentation of organic dye pollutants, photodegradation of food industrial wastewater and oxidation of methyl arenes which are converted into its respective aldehydes with moderate yields under visible light irradiation. The photooxidation reaction dependency on the intensity of the visible light was also studied. With the increase in the dosage of photocatalyst, the methyl groups are oxidized to get aldehydes and mono acid products, which are also identified from LC-MS data. Finally, [Zn(PPMHT)Cl] is with better efficiency than [Zn(PTHMT)Cl] and [Zn(MIMHPT)Cl] for oxidation of methyl arenes is reported under visible-light-driven conditions.
- Ahemed, Jakeer,Bhongiri, Yadagiri,Chetti, Prabhakar,Gade, Ramesh,Kore, Ranjith,Pasha, Jakeer,Pola, Someshwar,Rao D, Venkateshwar
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- A metal-free heterogeneous photocatalyst for the selective oxidative cleavage of CC bonds in aryl olefins: via harvesting direct solar energy
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Selective cleavage of CC bonds is highly important for the synthesis of carbonyl containing fine chemicals and pharmaceuticals. Novel methodologies such as ozonolysis reactions, Lemieux-Johnson oxidation reaction etc. already exist. Parallel to these, catalytic methods using homogeneous catalysts also have been discovered. Considering the various advantages of heterogeneous catalysts such as recyclability and stability, couple of transition metal-based heterogeneous catalysts have been applied for this reaction. However, the pharmaceutical industries prefer to use metal-free catalysts (especially transition metal-free) to avoid further leaching in the final products. This is for sure a big challenge to an organic chemist and to the pharmaceutical industries. To make this feasible, a mild and efficient protocol has been developed using polymeric carbon nitrides (PCN) as metal-free heterogeneous photocatalysts to convert various olefins into the corresponding carbonyls. Later, this catalyst has been applied in the gram scale synthesis of pharmaceutical drugs using direct solar energy. Detailed mechanistic studies revealed the actual role of oxygen, the catalyst, and the light source.
- Das, Shoubhik,Hatami, Nareh,Jooss, Christian,Lange, Niklas Simon,Ronge, Emanuel,Schilling, Waldemar,Zhang, Yu
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supporting information
p. 4516 - 4522
(2020/08/10)
-
- Monodentate Transient Directing Group Enabled Pd-Catalyzed Ortho-C-H Methoxylation and Chlorination of Benzaldehydes
-
We report Pd-catalyzed ortho-C-H methoxylation and chlorination of benzaldehydes by employing monodentate transient directing groups (TDGs) as an alternative strategy to bidentate TDGs. More importantly, a single crystal of benzaldehyde imine ortho-cyclopalladium intermediate was successfully obtained, and its structure was unambiguously determined by X-ray diffraction, which clearly showed that it was a binuclear palladium species bridged by a pyridone ligand. The utility of this approach was further demonstrated through the synthesis of key intermediates of natural products and drugs.
- Li, Feng,Zhou, Yirong,Yang, Heng,Wang, Ziqi,Yu, Qinqin,Zhang, Fang-Lin
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supporting information
p. 3692 - 3695
(2019/05/24)
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- Enantioselective Total Synthesis and Assignment of the Absolute Configuration of the Meroterpenoid (+)-Taondiol
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The first enantioselective total synthesis of (+)-taondiol, a pentacyclic marine meroterpenoid, has been achieved, which in addition to confirming the structure also established the absolute configuration of the natural product. The notable points in the synthetic route are synthesis of a highly functionalized tricyclic diterpenoid moiety starting from an enantiopure Wieland-Miescher ketone derivative in concise manner via Robinson-type annulation and an elegant hydrogen atom transfer olefin reduction followed by Lewis acid-catalyzed Friedel-Crafts reaction for one-pot C-C and C-O bond formations resulting in construction of the pentacyclic meroterpenoid skeleton.
- Dethe, Dattatraya H.,Mahapatra, Samarpita,Sau, Susanta Kumar
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supporting information
p. 2766 - 2769
(2018/05/22)
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- Synthesis method of pharmaceutical intermediate 2,4,5-trimethoxybenzoic acid
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The invention discloses a synthesis method of a pharmaceutical intermediate 2,4,5-trimethoxybenzoic acid. The synthesis method takes 1,2,4-trimethoxybenzene, DMF (Dimethyl Formamide), phosphoryl chloride, 2,4,5-trimethoxybenzaldehyde, silver nitrate, acetonitrile, hydrogen peroxide, zirconium oxide and MCM-41 as main raw materials, and MCM-41 zeolite powder is subjected to short-chain modificationby adopting tetraethyl orthosilicate TEOS; ultrasonic treatment is carried out on a mixed alkali solution and metal ion frameworks of nickel nitrate and aluminum nitrate are used for replacing to form a unique space three-dimensional framework structure with catalytic activity. According to the synthesis method disclosed by the invention, the disadvantages that products are complicated, the products are difficultly completely purified and the like, caused by drastic oxidization reaction of traditional benzaldehyde, are overcome by an intermediate catalyst, and the intermediate catalyst has anexcellent catalysis effect on synthesis reaction of the 2,4,5-trimethoxybenzoic acid.
- -
-
Paragraph 0008; 0019-0022
(2018/09/08)
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- Toward the total synthesis of citreamicin η: Synthesis of the pentacyclic core and GAB-ring annelation model studies
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A short 11-step synthesis of the pentacyclic core of the polycyclic xanthone antibiotic citreamicin η has been completed. Although the basic approach was inspired by our previous explorations of polycyclic xanthone chemistry, the present report features some new insights into the Moore rearrangement and offers some improvements to our original methodology that include additions of aryllithiums to squarate esters, additions of cerium acetylides to hindered ketones utilizing PDA as an internal indicator, and the use of cyclic di-tert-butylsilyl (DTBS) ethers to protect electron-rich benzyl alcohols toward ionization under acidic conditions. We also developed an improved protocol for selective o-bromination of phenols utilizing N-bromosuccinimide (NBS) and tetramethylguanidine (TMG) that promises to be generally useful. Finally, we developed a modular approach for the synthesis of isoquinolones and dihydro-5H-oxazolo[3,2-b]isoquinoline-2,5(3H)-diones that features a novel sequence of alkoxycarbonylation, acetone arylation, transamidation.
- Blumberg, Shawn,Martin, Stephen F.
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p. 4981 - 4993
(2018/05/23)
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- One-pot solvent-free synthesis of triaryl- and triheteroarylmethanes by Bi(OTf)3-catalyzed Friedel-Crafts reaction of arenes/heteroarenes with trialkyl orthoformates
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A convenient, practical and highly efficient one-pot method has been developed for the synthesis of triaryl- and triheteroarylmethane derivatives by Bi(OTf)3-catalyzed Friedel-Crafts alkylation of trialkyl orthoformates in combination with a wide variety of arenes/heteroarenes at room temperature under solvent-free conditions and in an air atmosphere. The methodology offers an operational simplicity, high atom economy and environmentally benign procedure. Furthermore, selected compound 3k showed promising anti-inflammatory activity with inhibition nitric oxide and did not exhibit significant cytotoxic effects on macrophage cells.
- Tuengpanya, Surisa,Chantana, Chayamon,Sirion, Uthaiwan,Siritanyong, Wipada,Srisook, Klaokwan,Jaratjaroonphong, Jaray
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p. 4373 - 4380
(2018/07/21)
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- Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl) methane
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Difluoro(phenylsulfanyl)methane (PhSCF 2 H) was found to undergo a reaction with aromatic compounds mediated by SnCl 4, through a thionium intermediate characterized by NMR and TD-DFT analyses, leading to the formation of a mixture of S, S ′-diphenyl dithioacetal and aromatic aldehyde which, after oxidative hydrolysis, provides the aromatic aldehyde in good to excellent yields. The salient feature of the present work is the reaction of activated aromatic compounds containing a deactivating ester functional group, leading to the formylated products in good yields.
- Betterley, Nolan M.,Kongsriprapan, Sopanat,Chaturonrutsamee, Suppisak,Deelertpaiboon, Pramchai,Surawatanawong, Panida,Pohmakotr, Manat,Soorukram, Darunee,Reutrakul, Vichai,Kuhakarn, Chutima
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p. 2033 - 2040
(2018/03/21)
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- Visible light mediated chemo-selective oxidation of benzylic alcohols
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A highly chemoselective visible light mediated strategy has been developed for oxidation of benzylic alcohols. The method circumvents the use of toxic metal catalysts, high energy light source, and operates at room temperature. Furthermore reaction is easily scalable to gram levels.
- Devari, Shekaraiah,Rizvi, Masood Ahmad,Shah, Bhahwal Ali
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supporting information
p. 3294 - 3297
(2016/07/11)
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- Alkylbenzoquinone involved in development of cellular slime molds
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The structure of the prespore-cell-promoting factor from Dictyostelium discoideum was determined to be 2-hydroxy-5-methyl-6-pentylbenzoquinone. The synthetic compound has prespore-cell-promoting activity similar to the natural one, with half-maximal induction at a concentration as low as 40 pM. It was also found that the factor induces aggregation in an aggregation-deficient mutant of a related species, Polysphodilium violaceum. Both these activities are sensitive to positional isomerism with the 6-methyl-5-pentyl isomer showing no detectable activity.
- Takaya, Yoshiaki,Hotta, Rie,Fujiwara, Kenshu,Otani, Risa,Uchiyama, Yurika,Sakakibara, Mizuki,Fukuda, Eri,Niwa, Masatake,Inouye, Kei,Oohata, Akiko A.
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p. 3660 - 3663
(2014/08/05)
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- CuI/N4 ligand/TEMPO derivatives: A mild and highly efficient system for aerobic oxidation of primary alcohols
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A new system consisting of a copper(I) complex generated in situ from a tetradentate nitrogen ligand and CuI in combination with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives was successfully developed. The system was suitable for efficient and selective aerobic oxidation of primary benzyl and allyl alcohols with a wide range of functional groups to the corresponding aldehydes at room temperature. The best result was obtained with N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine as the ligand and 4-OH-TEMPO as a cocatalyst in CH3CN. In addition, high-resolution mass spectrometry, ultraviolet-visible spectroscopy, and electrochemical experiments were used to provide evidence of intermediates.
- Zhang, Shufang,Miao, Chengxia,Xu, Daqian,Sun, Wei,Xia, Chungu
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p. 1864 - 1873
(2015/09/28)
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- Synthesis and SAR investigation of natural phenylpropene-derived methoxylated cinnamaldehydes and their novel Schiff bases as potent antimicrobial and antioxidant agents
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A series of cinnamyl compounds were synthesized from abundantly available methoxylated phenylpropenes and evaluated for their antimicrobial activity by the broth microdilution method against fourteen opportunistic bacterial and fungal human pathogens. Structure-activity relationship studies indicated that methylenedioxy cinnamaldehyde exhibited promising broad-spectrum activity against the tested microorganisms and hence was used as a lead structure to synthesize novel Schiff bases/heterocyclic compounds (23-33) under microwave irradiation. Out of these, thiazole-based Schiff bases have shown promising antibacterial activity against B. subtilis (26; MIC 0.12 mM), M. luteus (27; MIC 0.20 mM), and S. aureus (27; MIC 0.20 mM). Also, the compounds 23-33 were investigated for in vitro antioxidant activity using DPPH? assay where compound 28 showed a maximum of 80.71 % inhibition.
- Sharma, Upendra K.,Sood, Swati,Sharma, Nandini,Rahi, Praveen,Kumar, Rakesh,Sinha, Arun K.,Gulati, Arvind
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p. 5129 - 5140
(2013/12/04)
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- Synthesis, anticancer and antioxidant activities of 2,4,5-trimethoxy chalcones and analogues from asaronaldehyde: Structure-activity relationship
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2,4,5-Trimethoxy chalcones and analogues were synthesized from asaronaldehyde derived from β-asarone. These novel compounds when tested against three human tumour cell lines (MCF-7, SW-982 and HeLa) using MTT assay, revealed that chalcones possessing electron donor groups in para position to carbonyl moiety of phenyl ring A, showed better inhibitory activity (2, 3, 4, 6, 7, 10, 17). When evaluated for antioxidant activities, compound 15 exhibited better free radical scavenging property in DPPH assay while compounds 2, 3, 5, 7, 9, 10, 11, 16, and 18 showed significant NO scavenging activity. All compounds exhibited very good phenyl hydrazine induced haemolysis of erythrocytes in phenylhydrazine assay. Structure-activity relationship (SAR) study using in-silico analysis matched well with in-vitro tumour cell inhibitory activity.
- Shenvi, Suvarna,Kumar, Krishna,Hatti, Kaushik S.,Rijesh,Diwakar, Latha,Reddy, G. Chandrasekara
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p. 435 - 442
(2013/05/21)
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- Chalcones as promising pesticidal agents against diamondback moth (Plutella xylostella): Microwave-assisted synthesis and structure-activity relationship
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A series of chalcones (A-CH=CH-CO-B) were synthesized under microwave irradiation, and for the first time their pesticidal activity against diamondback moth (Plutella xylostella) was evaluated to identify the promising lead structures. The structure-activity relationship (SAR) analysis revealed that electron-withdrawing substituents on ring A of chalcone provided good pesticidal agents, whereas, ring B can bear either electron-withdrawing or electron-releasing substituents. Moreover, compound 22 having para-Cl substitution on ring A as well on ring B showed maximum activity with LC 50 value of 170.24 μg mL-1. Springer Science+Business Media, LLC 2011.
- Kumar, Rakesh,Sharma, Prabha,Shard, Amit,Tewary, Dhananjay Kumar,Nadda, Gireesh,Sinha, Arun Kumar
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experimental part
p. 922 - 931
(2012/08/14)
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- Copper(II)-catalyzed aerobic oxidative synthesis of substituted 1,2,3- and 1,2,4-triazoles from bisarylhydrazones via C-H functionalization/C-C/N-N/C-N bonds formation
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An unprecedented copper(II)-catalyzed aerobic oxidative synthesis of 2,4,5-triaryl-1,2,3-triazoles and 1,3,5-triaryl-1,2,4-triazoles from bisarylhydrazones as the common starting precursor has been achieved via cascade C-H functionalization/C-C/N-N/C-N bonds formation under mild reaction conditions. One of the enthralling outcomes of this strategy is the copper(II)-catalyzed room temperature C-H functionalization/C-N bond formation in presence of air, which has been accomplished during the synthesis of substituted 1,2,4-triazoles. This new class of compounds could give prospective luminescence as an iconic component in the area of pharmaceutical and biological sciences. The intermediates for both the processes have been isolated to elucidate the mechanistic scenario.
- Guru, Murali Mohan,Punniyamurthy, Tharmalingam
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experimental part
p. 5063 - 5073
(2012/07/16)
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- Copper catalyzed oxidation of benzylic alcohols in water with H 2O2
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A straightforward, efficient and sustainable copper catalyzed method was developed for oxidation of benzylic alcohols with 30% H2O2 in water. The reaction proceeded with CuSO4 catalyst (1 mol%) at 100 °C without additional base or ligand. Primary benzylic alcohols were converted almost quantitatively to aldehydes with 70-90% selectivity, corresponding acids being the major side products. Also secondary benzylic alcohols afforded the corresponding ketones in high conversion with selectivities greater than 90%. It was demonstrated that the CuSO4 catalyst can be recycled and reused at least for three runs, even though with some loss of catalytic activity. Selectivity of the CuSO4 based catalyst system could be further increased by using 2-N-(p-fluorophenyl)- pyrrolecarbaldimine (1) as a ligand in combination with TEMPO in K 2CO3 solution. The catalyst system was individually optimized (1 mol% CuSO4, 2 mol% 1, 0.1 M K2CO3 and 5 mol% TEMPO) for a wide range of benzylic and allylic alcohols, which were quantitatively and selectively converted into the corresponding aldehydes with 3 eq. of H2O2 in 1 h.
- Ahmad, Jahir Uddin,R?is?nen, Minna T.,Leskel?, Markku,Repo, Timo
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experimental part
p. 180 - 187
(2012/02/04)
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- Tandem allylic oxidation-condensation/esterification catalyzed by silica gel: An expeditious approach towards antimalarial diaryldienones and enones from natural methoxylated phenylpropenes
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A new one-pot strategy has been developed, wherein abundantly available methoxylated phenylpropenes are directly transformed into corresponding dienones (1,5-diarylpenta-2,4-dien-1-ones) and enones (chalcones and cinnamic esters) via allylic oxidation-condensation or allylic oxidation-esterification sequences. Preliminary antimalarial activity studies of the above synthesized diaryldienones and enones against Plasmodium falciparum (Pf3D7) have shown them to be promising lead candidates for developing newer and economical antimalarial agents. In particular, two enones (12b and 13b) were found to possess comparatively better activity (IC50 = 4.0 and 3.4 μM, respectively) than licochalcone (IC50 = 4.1 μM), a well known natural antimalarial compound. The Royal Society of Chemistry 2011.
- Sharma, Abhishek,Sharma, Naina,Shard, Amit,Kumar, Rakesh,Mohanakrishnan, Dinesh,Saima,Sinha, Arun K.,Sahal, Dinkar
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supporting information; experimental part
p. 5211 - 5219
(2011/08/07)
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- Reinvestigation of structure-activity relationship of methoxylated chalcones as antimalarials: Synthesis and evaluation of 2,4,5-trimethoxy substituted patterns as lead candidates derived from abundantly available natural β-asarone
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We have examined the antimalarial structure-activity relationship of a series of methoxylated chalcones (A-CHCH-CO-B) against Plasmodium falciparum (3D7 strain) using fluorescence-based SYBR Green assay. Our study has revealed that electron releasing methoxy groups on ring A and electron withdrawing groups on ring B increases antimalarial potency while the positional interchange of these groups causes a decrease. In particular, 2,4,5-trimethoxy substitution pattern at ring A provided potent analogues which were easily derived from abundantly available natural β-asarone rich Acorus calamus oil. Cytotoxic evaluation indicated that the most active compounds 27 (IC50: 1.8 μM) and 26 (IC50: 2 μM) were also relatively non-toxic. Furthermore, compound 12 showed excellent resistance index of 1.1 against chloroquine resistant Dd2 strain of P. falciparum.
- Kumar, Rakesh,Mohanakrishnan, Dinesh,Sharma, Abhishek,Kaushik, Naveen Kumar,Kalia, Kalpana,Sinha, Arun Kumar,Sahal, Dinkar
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experimental part
p. 5292 - 5301
(2011/02/23)
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- Orthoamides, LXVII [1]. Bis(diformylamino)methane - A new efficient formylating reagent for aromatic compounds
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Formaldehyde reacts with diformamide (10) to give N-(hydroxymethyl) diformamide (11), which upon treatment with thionylchloride yields N-(chlormethyl)diformamide (12) together with small amounts of oxydimethylenebis(diformamide) (13). Various diformylamine derivatives, such as diformylaminomethyl formiate (14), diformylaminomethylisothiocyanate (15) and the N-diformylaminomethylated guanidinium salt 16, can be prepared from 12. Bis(diformylamino) methane (7) can be obtained by the reaction of sodium diformamide (8) with either 1-(chloromethyl)pyridinium chloride (9) or N-(chloromethyl)diformamide (12) in acetonitrile. The action of tris(chloromethyl) amine (18) on sodium diformamide (8) affords tris(diformylaminomethyl)amine (19). The constitution of the compounds 7,11 and 19 was confirmed by crystal structure determination. The nature of the products from the reactions of aromatic compounds with 12 depends on the Lewis acid which is used as activator. Thus the N-benzylformamides 20a, b can be obtained from toluene and mesitylene and 12/BF3-ether, whereas 1,2,4- trimethoxybenzene is formylated by 12/AlCl3 to give the aldehyde 22. Interestingly enough, a novel and efficient formylating reagent resulted from these investigations: bis(diformylamino)methane (7), which can be activated by Lewis acids, e. g. AlCl3. The scope of this procedure is comparable with that of the Olah-formylation method (formylfluoride/BF3).
- Kantlehner, Willi,Anders, Ernst,Mezger, Jochen,Stoyanov, Edmont V.,Kre?, Ralf,Wermann, Kurt,Frey, Wolfgang,G?rls, Helmar
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experimental part
p. 395 - 406
(2009/01/31)
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- Synthesis and electronic absorption and fluorescence of 2-arylbenzothiazole derivatives
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A series of new 2-arylbenzothiazoles have been prepared in high yields by Jacobson's cyclization condensation of 2-aminobenzenethiol with benzoyl chloride or benzaldehyde derivatives under three different routes. These compounds have been fully characterized by EA, IR, NMR and MS. The electronic absorption and fluorescence of these compounds have been systematically investigated for the first time. The relationships between their photophysical properties and structures have been discussed. The alteration of absorption and emission wavelengths can be elucidated by Hammett's substituent constants.
- Chen, Lianqing,Yang, Chuluo,Li, Suyue,Qin, Jingui
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p. 317 - 322
(2008/02/13)
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- TEMPO-copper(II) diimine-catalysed oxidation of benzylic alcohols in aqueous media
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In situ generated copper(II)-diimine complexes combined with TEMPO (2,2,6,6-tetramethyl-piperidinyl-1-oxyl radical) were studied in the oxidation of benzylic alcohols, the focus being on enviromentally benign reaction conditions. In this respect, reactions were studied in aqueous alkaline solutions and dioxygen was used as an end oxidant. This simple catalytic system turned out to be highly efficient and selective in the oxidation of primary and secondary benzylic alcohols to their corresponding carbonyl compounds. Under optimised reaction conditions [5 mol% of TEMPO, 3 mol% of copper(II) diimine, pH 12.6-13.5, 80°C, 10 bar O2] benzyl alcohol was quantitatively and selectively oxidised to benzaldehyde. According to ESI-MS studies, coordination of TEMPO, as well as deprotonated benzyl alcohol to the parent copper-diimine complex in aqueous solutions is feasible. Supported by these observations a plausible reaction mechanism is proposed for the oxidation reaction.
- Figiel, Pawel J.,Leskelae, Markku,Repo, Timo
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p. 1173 - 1179
(2008/03/27)
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- Kinetics of oxidation of benzyl alcohols by the dication and radical cation of ABTS. Comparison with laccase-ABTS oxidations: An apparent paradox
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Laccase, a blue copper oxidase, in view of its moderate redox potential can oxidise only phenolic compounds by electron-transfer. However, in the presence of ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) as a redox mediator, laccase reacts with the more difficult to oxidise non-phenolic substrates, such as benzyl alcohols. The role of ABTS in these mediated oxidations is investigated. Redox interaction with laccase could produce in situ two reactive intermediates from ABTS, namely ABTS++ or ABTS ?+. These species have been independently generated by oxidation with Ce(IV) or Co(III) salts, respectively, and their efficiency as monoelectronic oxidants tested in a kinetic study towards a series of non-phenolic substrates; a Marcus treatment is provided in the case of ABTS ++. On these grounds, intervention of ABTS++ as a reactive intermediate in laccase-ABTS oxidations appears unlikely, because the experimental conditions under which ABTS++ is unambiguously generated, and survives long enough to serve as a diffusible mediator, are too harsh (2 M H2SO4 solution) and incompatible with the operation of the enzyme. Likewise, ABTS?+ seems an intermediate of limited importance in laccase-ABTS oxidations, because this weaker monoelectronic oxidant is unable to react directly with many of the non-phenolic substrates that laccase-ABTS can oxidise. To solve this paradox, it is alternatively suggested that degradation by-products of either ABTS ++ or ABTS?+ are formed in situ by hydrolysis during the laccase-ABTS reactions, and may be responsible for the observed oxidation of non-phenolics. The Royal Society of Chemistry 2005.
- Branchi, Barbara,Galli, Carlo,Gentili, Patrizia
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p. 2604 - 2614
(2007/10/03)
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- An eco-friendly regeneration of aldehydes exploiting ammonium acetate under microwave irradiation
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A number of bisulphite addition products and diacetates are deprotected separately to the corresponding aldehydes exploiting a green reagent, ammonium acetate in solvent-free conditions under microwave irradiation by a rapid, clean, efficient and high yielding method under environmentally benign conditions.
- Mitra, Alok Kumar,Karchaudhuri, Nilay,De, Aparna
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p. 237 - 239
(2007/10/03)
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- Compositions containing aromatic aldehydes and their use in treatments
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Disclosed are pharmaceutical and cosmetic compositions containing aromatic aldehyde compounds. Some of the disclosed compositions are useful as topical therapeutics for treating inflammatory dermatologic conditions. Some of the compositions are useful in transdermal and other systemic dose forms for treating other inflammatory conditions in mammals.
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- Microwave-promoted Synthesis of Methoxylated Benzaldehydes from Natural cis-Phenylpropenes Using NaIO4/OsO4 (cat.)
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Microwave-promoted rapid oxidation of toxic natural cis-phenylpropenes (1a-1e) into high valued methoxylated benzaldehydes (2a-2e) was achieved within 2 min in high yield (71-84%) by reacting with sodium metaperiodate in the presence of catalytic amount of osmium tetraoxide (co-oxidant) and benzyltriethylammonium chloride (PTC).
- Sinha, Arun K.,Joshi, Bhupendra P.,Acharya, Ruchi
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p. 780 - 781
(2007/10/03)
-
- SAR studies of 3-cyclopropanecarbonyloxy-2-cyclohexen-1-one as inhibitors of 4-hydroxyphenylpyruvate dioxygenase
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Various 3-cyclopropanecarbonyloxy-2-cyclohexen-1-one 1 derivatives have been synthesized and tested as inhibitors of 4-hydroxyphenylpyruvate dioxygenase (4-HPPD) from pig liver. The inhibition results indicated that well-positioned dicarbonyl groups as well as the cyclopropyl group of 1 were essential for potent inhibition. Substitution at the 2-position of the ring system has a significant effect on inhibitor potency, while the 5-position can undergo substantial variations and retain inhibitor potency. In the compounds examined, 2-chloro substituted 12 is the best inhibitor of all with IC50 of 15 nM, the rest of the synthesized analogues were less potent inhibitors than the parent compound.
- Lin, Yung-Lung,Wu, Chung-Shieh,Lin, Shean-Woei,Huang, Jian-Lin,Sun, Yang-Sheng,Yang, Ding-Yah
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p. 685 - 690
(2007/10/03)
-
- Microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and cis-phenylpropenes: a commercial utilisation of toxic cis-isomer
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The present invention provides microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and cis-phenylpropene, a commercial utilization of toxic cis-isomer of the general formula (I) using meta-periodate and osmium tetraoxide (catalytic amount) as an efficient oxidizing agent in the presence of catalyst namely amberlite IRA-410 and quaternary ammonium salt.
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- Cation radical mechanisms - α, β, γtribenzoyloxylation of 2-allyl-1,4,5-trimethoxybenzene
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Threo- and erythro-1-(2,4,5,-trimethoxyphenyl-1,2,3-tri(4-nitro) benzoyloxypropanes were formed in a one-electron transfer reaction between 2-allyl-1,4,5-trimethoxybenzene and 4-nitrobenzoyl peroxide and a mechanism is proposed for this very unusual, subtle reaction.
- Zhao,Li,Zhao
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p. 430 - 432
(2007/10/03)
-
- Structural effects on the OH--promoted fragmentation of methoxy-substituted 1-arylalkanol radical cations in aqueous solution: The role of oxygen acidity
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A kinetic and product study of the OH--induced decay in H2O of the radical cations generated from some di- and tri-methoxy-substituted 1-arylalkanols (ArCH(OH)R·+) and 2- and 3-(3,4-dimethoxyphenyl) alkanols has been carried out by using pulse- and γ-radiolysis techniques. In the 1-arylalkanol system, the radical cation 3,4-(MeO)2C6H3CH2OH ·+ decay at a rate more than two orders of magnitude higher than that of its methyl ether; this indicates the key role of the side-chain OH group in the decay process (oxygen acidity). However, quite a large deuterium kinetic isotope effect (3.7) is present for this radical cation compared with its α-dideuterated counterpart. A mechanism is suggested in which a fast OH deprotonation leads to a radical zwitterion which then undergoes a rate-determining 1,2-H shift, coupled to a side-chain-to-ring intramolecular electron transfer (ET) step. This concept also attributes an important role to the energy barrier for this ET, which should depend on the stability of the positive charge in the ring and, hence, on the number and position of methoxy groups. On a similar experimental basis, the same mechanism is suggested for 2,5-(MeO)2C6H3CH2OH ·+ as for 3,4-(MeO)2C6H3CH2OH ·+, in which some contribution from direct C-H deprotonation (carbon acidity) is possible. In fact, the latter process dominates the decay of the trimethoxylated system 2,4,5-(MeO)3C6H2CH2OH ·+, which, accordingly, reacts with OH- at the same rate as that of its methyl ether. Thus, a shift from oxygen to carbon acidity is observed as the positive charge is increasingly stabilized in the ring; this is attributed to a corresponding increase in the energy barrier for the intramolecular ET. When R = tBu, the OH--promoted decay of the radical cation ArCH(OH)R·+ leads to products of C-C bond cleavage. With both Ar = 3,4- and 2,5-dimethoxyphenyl the reactivity is three orders of magnitude higher than that of the corresponding cumyl alcohol radical cations; this suggests a mechanism in which a key role is played by the oxygen acidity as well as by the strength of the scissile C-C bond: a radical zwitterion is formed which undergoes a rate-determining C-C bond cleavage, coupled with the intramolecular ET. Finally, oxygen acidity also determines the reactivity of the radical cations of 2-(3,4-dimethoxyphenyl)ethanol and 3-(3,4-dimethoxyphenyl)propanol. In the former the decay involves C-C bond cleavage, in the latter it leads to 3-(3,4-dimethoxyphenyl) propanal. In both cases no products of C-H deprotonation were observed. Possible mechanisms, again involving the initial formation of a radical zwitterion, are discussed.
- Baciocchi, Enrico,Bietti, Massimo,Gerini, Maria Francesca,Manduchi, Laura,Salamone, Michela,Steenken, Steen
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p. 1408 - 1416
(2007/10/03)
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- 2,4,5-Trimethoxycinnamaldehyde from Caesulia axillaris Roxb.
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Acetone extract of Caesulia axillaris Roxb. has yielded a new aromatic 2,4,5-trimethoxycinnamaldehyde along with the known γ-asarone and 2,4,5-trimethoxycinnamaldehyde.The structure of the new aldehyde has been established by spectral data and synthesis.
- Kulkarni, Mandakini M.,Sohoni, Jayant S.,Rojatkar, Supada R.,Nagasampagi, Bhimsen A.
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p. 981 - 982
(2007/10/02)
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- Photooxidation of β-Asarone
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Exposure of β-cis-asarone (1) as neat oil to sunlight for a month gives five photoproducts characterised as β-trans-asarone (2), (E)-(3)- and (Z)-(4)-3-(2,4,5-trimethoxyphenyl)-propen-2-als, asaraldehyde (5) and acoradin (6).All the products have been identified on the basis of their spectral data.A reaction mechanism leading to the formation of photoproducts is suggested.
- Saxena, D. B.,Mukerjee, S. K.
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p. 683 - 684
(2007/10/02)
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- Studies on the chemical constituents of rutaceous plants. XLIX. Development of a versatile method for the synthesis of antitumor-active benzo[c]phenanthridine alkaloids. (1). Preparation of various 2,4-bisaryl-4-oxobutyronitriles and 2,4-bisaryl-4-oxobutyramides
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For the sake of establishment of a versatile synthetic method for benzo[c]phenanthridine alkaloids, improvement of the Robinson synthetic method was examined. Thirteen chalcones (7a-m) were prepared by condensation of two acetophenone derivatives (15 and 16) with eleven benzaldehyde derivatives (19a-k) as fundamental starting materials. Hydrocyanation of these chalcones (7a-1) except one (7m) gave the corresponding 2,4-bisaryl-4-oxobutyronitriles (8a-1). Eleven 2,4-bisaryl-4-oxobutyramides (9a-k) were also prepared.
- Ishii,Ishikawa,Deushi,et al.
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p. 3024 - 3038
(2007/10/02)
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