- DUAL PHOTOREACTIONS OF PHTHALAZINE FROM THE LOWEST EXCITED SINGLET AND TRIPLET STATES
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Phthalazine undergoes the photoreduction and the photo-reductive dimerization simultaneously to give 1,2-dihydrophthalazine and its dimer (1H,1'H,2H,2'H-1,1'-biphthalazine), respectively, upon ultraviolet light irradiation in 2-propanol.It has been suggested that the photoreduction proceeds through the lowest excited singlet state and the photodimerization through the lowest triplet state.
- Sano, Ryo,Inoue, Hiroyasu
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Read Online
- Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
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Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
- An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
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supporting information
p. 2876 - 2894
(2021/02/01)
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- Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
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A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
- Kim, Kyu Dong,Lee, Jun Hee
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supporting information
p. 7712 - 7716
(2019/01/03)
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- Ligand Redox-Controlled Tandem Synthesis of Azines from Aromatic Alcohols and Hydrazine in Air: One-Pot Synthesis of Phthalazine
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A controlled tandem synthetic route to azines from various alcohols and hydrazine hydrate by the use of a Ni(II) complex of 2,6-bis(phenylazo)pyridine as a catalyst is reported. In marked contrast to the previous report, the reaction is operative using an earth-abundant metal catalyst, milder reaction conditions, and aerobic conditions, which though are desirable but unprecedented in the literature. The catalytic reaction has a vast substrate scope including a single-step synthesis of phthalazine from 1,2-benzenedimethanol and hydrazine hydrate via intramolecular coupling. Mechanistic investigation suggests that the coordinated ligand redox controls the reaction by the use of a reversible azo (N=N)/ hydrazo (NH - NH) redox couple where the metal center is used primarily as a template.
- Chakraborty, Mou,Sengupta, Debabrata,Saha, Tanushri,Goswami, Sreebrata
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supporting information
p. 7771 - 7778
(2018/06/11)
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- Nitrogen activation and conversion method promoted by divalent rare earth iodine compound
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The invention belongs to the technical field of organic chemical synthesis, and particularly relates to a method for activating and converting nitrogen through a divalent rare earth compound. A divalent rare earth diodide is used as a reducing agent, a solvent is added in, the mixture reacts with nitrogen, then a hydrogen source is added in, and then the mixture reacts with an aldehyde or ketone compound to obtain an azine or pyridazine compound. According to the method, the nitrogen is activated and converted into the organic compound containing nitrogen on the mild condition. Compared with a classical ammonia synthesis path, strict reaction conditions such as high temperature, high pressure and ammonia oxidation are avoided, and the method is of great significance in developing the new technology of nitrogen molecule activation and broadening the application range of rare earth metal in organic synthesis.
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Paragraph 0027; 0028
(2016/12/01)
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- One-pot synthesis of phthalazines and pyridazino-aromatics: A novel strategy for substituted naphthalenes
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A new one-pot strategy for the synthesis of phthalazines and pyridazino-aromatics starting from aromatic aldehydes has been developed. A variety of substituents ranging from electron withdrawing to donating is tolerated furnishing the desired 1,2-diazine in good to excellent yields. The products have been applied to the bidentate Lewis acid catalyzed inverse electron-demand Diels-Alder (IEDDA) reaction opening a novel two-step entry into substituted naphthalenes, such as Naproxen.
- Kessler, Simon N.,Wegner, Hermann A.
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supporting information; experimental part
p. 3268 - 3271
(2012/08/28)
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- Pyridinium chloride: A new reagent for N-demethylation of N-methylazinium derivatives
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A new N-demethylation reaction of N-methylazinium derivatives by using boiling pyridinium chloride is described. The reaction is quite clean, fast and yields are almost quantitatives.
- Ruiz, Anthony,Rocca, Patrick,Marsais, Francis,Godard, Alain,Queguiner, Guy
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p. 6205 - 6208
(2007/10/03)
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- Aryl-fused and hetaryl-fused-2,4-diazepine and 2,4-diazocine antiarrhythmic agents
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Aryl-fused- and hetaryl-fused-2,4-diazepines of formula XXXVI, benzodiazocines of formula XXX, benzodiazepines of formula II STR1 δ-aminoamides of formula III and aryldimethanamines of formula XXXVII STR2 wherein A is an aryl or hetaryl ring; R1 is hydrogen, alkyl, aryl or hetaryl; R2 is hydrogen, alkyl, substituted alkyl, or aryl; R3 is alkyl, aryl, aralkyl or heteroatom substituted alkyl or aralkyl; R4 is hydrogen or alkyl; R5 is hydrogen, alkyl, aryl or hetaryl; R6 is hydrogen, alkyl, alkoxy, halogen or a fused benzene ring; R9 is hydrogen, alkyl, or substituted alkyl; and R10 is hydrogen, alkyl, or substituted alkyl. The invention further relates to processes for the preparation of, pharmaceutical compositions containing, and methods of treating cardiac arrhythmia with the compounds of formulas XXXVI, XXX, II, III, and XXXVII.
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- Electron-transfer Reactions. I. The Application of Derivative Linear-sweep Voltammetry for the Determination of the Rate Constants for Electron Transfer between Two Different Organic Anion Radicals
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The kinetic of homogeneous electron-transfer reactions between different anion radicals, A-. and B-. can be conveniently studied by derivative linear-sweep voltammetry under conditions where the dianions, B2-, are rapidly protonated. The method involves measurements of the ratio, R'I(A/B) = I'A/I'B, where I'A and I'B are the maximum values of dI/dt for the reduction of A and B, at different sweep rates for solutions containing both substrates.Working curves have been calculated by digital simulation for the concentration ratios, C0B/C0A = 1, 2, 5 and 10.The approximate kinetic range of the method is given by expression (ii). 104 1/(dm3 mol-1 s-1) 8 (ii) The application of this type of measurement is illustrated by the electron transfer from the anion radicals, A-., of several aromatic compounds to the anion radicals, B-., of azobenzene and 4,4'-dimethylazobenzene.The fit of the experimental data to the working curves is generally excellent for substrates having similar diffusion coefficients.The measured rate constants vary from 2.5x106 dm3 mol-1 s-1, for A = phthalazine and B = azobenzene, to 2.7x104 dm-3 mol-1 s-1, for A = anthracene and B = 4,4'-dimethylazobenzene.
- Ingemann, Steen,Nielsen, Merete Folmer,Hammerich, Ole
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p. 583 - 591
(2007/10/02)
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- Some Reactions of N-Alkoxycarbonyl Reissert Compounds with Heterocumulenes: Formation of the Imidazoisoquinoline and Imidazophthalazine Systems and Related Chemistry
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Chloroformate derived Reissert compounds of isoquinoline and of phenanthridine on treatment with base undergo cyclisation with isothiocyanates to give in good yields corresponding imidazoisoquinoline and imidazophenanthroline derivatives.Phthalazine Reissert compound analogues give open chain adducts under the same conditions which can be cyclised to derivatives of the novel imidazophthalazine system by heating in the presence of molecular sieves.When carbon disulphide is the heterocumulene cyclisation is not observed but open chain dithio-ester derivatives can be isolated on alkylation of the intermediate sodium salts.
- Uff, Barrie C.,Budhram, Ronald S.,Ghaem-Maghami, Ghobad,Mallard, Angela S.,Harutunian, Vahak,et al.
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p. 1901 - 1930
(2007/10/02)
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- Nature of Reissert Analogs Derived from N,N-Dialkyl and N,N-Diaryl Carbamoyl Chlorides
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Reissert analogs were prepared from the reaction of isoquinoline and phthalazine with carbamoyl chlorides and cyanide using the methylene chloride-water method.Alkylation, condensation, Michael addition, and hydrolysis reactions of these Reissert analogs have been studied and found in many cases, to be similar to those of the isoquinoline Reissert compound.
- Kant, Joydeep,Popp, Frank D.,Uff, Barrie C.
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p. 1065 - 1070
(2007/10/02)
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- Diazaarynes: 3,4- and 4,5-Didehydropyridazine By Electron Impact and Thermolytic Fragmentation of The Corresponding Dicarboxylic Anhydrides
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The new hetarynes (1) and (2) heve been advanced as intermediates in the vapour phase both for the electron impact and the pyrolytic fragmentation pattern of pyridazine-3,4- and 4,5-dicarboxylic acid anhydrides (10) and (11), respectively.The presence of a peak at m/e 78 in the mass spectra of these compounds, as well as the formation of the diazanaphtalenes (12) and (13), respectively, from their thermolysis in benzene, appeared to support this proposal.
- Sio, Francesco De,Chimichi, Stefano,Nesi, Rodolfo,Cecchi, Lucia
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p. 1427 - 1429
(2007/10/02)
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- PHTHALAZINE DERIVATIVES FROM AROMATIC ALDAZINES
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A Lewis acid mediated synthesis of phthalazine derivatives II and III from aromatic aldazines I is reported.
- Robev, Stefan K.
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p. 345 - 348
(2007/10/02)
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- A Search for Lone-Pair Interactions in Forward and Reverse Menschutkin Reactions of Some Diaza Heterocycles
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The rates of methylation (forward reaction) of phthalazine (1), 1,8-naphthyridine (2), 1,10-phenanthroline (3), and of some ring methyl derivatives are compared with the rates of demethylation of the corresponding N-methyl quaternary iodides.It was observed for (2), and especially for (3), that a nitrogen lone pair in place of a CH group (quinoline and 8-methylquinoline, respectively) aids the forward reaction but does not have a commensurate retarding effect on the reverse process.In contrast to (3), 2,2'-bipyridine showed behaviour typical of α-substituted pyridines.The introduction of a 2-methyl group into (3) had an appreciable rate-enhancing effect on methylation (at N 10) and this is interpreted as evidence for lone-pair cooperativity in the forward reaction
- Deady, Leslie W.
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p. 163 - 170
(2007/10/02)
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- Coenzyme A: pKa and γ Values
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The pKa and γ values at 25 deg C, I 0.1 M, of the mercapto group of coenzyme A, were calculated to be 10.35+/-0.15 and 0.70+/-0.02 respectively.The γ value was calculated from differences in the parition coefficient of quinazoline between cyclohexane and aqueous buffers and that between cyclohexane and aqueous buffers which contained coenzyme A.The described procedure could be used to obtain γ values of other nucleophilic reagents which, like coenzyme A, absorb u.v. energy strongly.
- Pitman, Ian H.,Morris, Ian J.
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p. 1625 - 1630
(2007/10/02)
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