- DECOMPOSITION IN APROTIC SOLVENTS OF 2,4-DIHYDROXY-7-METHOXY-1,4-BENZOXAZIN-3-ONE, A HYDROXAMIC ACID FROM CEREALS
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The decomposition of the title compound (DIMBOA, 1) in aprotic solvents was analysed in terms of linear solvation energy relationships using donor numbers.The results indicate rate-limiting cyclic hemiacetal opening in low donor number solvents and rate-limiting isocyanate formation in high donor number solvents.The addition of H2O to DIMBOA decomposing in high donor number solvents had no effect upon the reaction rate, allowing one of the two proposed mechanisms to be rejected.
- Bravo, Hector R.,Niemeyer, Hermann M.
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- REACTION OF DIMBOA WITH AMINES
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DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a hydroxamic acid from cereals, reacted with primary amines to give an addition compound with two imino groups.Kinetic studies with DIMBOA and with the DIMBOA analogues 2,7-dimethoxy-1,4-benzoxazin-3-one and 2-hydroxy-7-methoxy-1,4-benzoxazin-3-one indicated that the reaction occurred through the intermediacy of the aldol tautomer of DIMBOA.The data is discussed in relation to the biological activyty of DIMBOA. Key Word Index - DIMBOA; hydroxamic acids; Gramineae; plant defence; anti inflamatory activity.
- Perez, Francisco J.,Niemeyer, Hermann M.
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- Versatile Cp*Co(III)(LX) Catalyst System for Selective Intramolecular C-H Amidation Reactions
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Herein, we report the development of a tailored cobalt catalyst system of Cp*Co(III)(LX) toward intramolecular C-H nitrene insertion of azidoformates to afford cyclic carbamates. The cobalt complexes were easy to prepare and bench-stable, thus offering a convenient reaction protocol. The catalytic reactivity was significantly improved by the electronic tuning of the bidentate LX ligands, and the observed regioselectivity was rationalized by the conformational analysis and DFT calculations of the transition states. The superior performance of the newly developed cobalt catalyst system could be broadly applied to both C(sp2)-H and C(sp3)-H carbamation reactions under mild conditions.
- Chang, Sukbok,Jung, Hoimin,Kim, Dongwook,Lee, Jeonghyo,Lee, Jia,Park, Juhyeon
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supporting information
p. 12324 - 12332
(2020/08/06)
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- Synthesis of benzoxazolones from nitroarenes or aryl halides
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Chemical equation presented A simple and effective method for the preparation of benzoxazolones from nitroarenes or aryl halides is described. Partial reduction of a nitro group in the presence of a chloroformate followed by a microwave-assisted rearrangement/ring closure sequence provides a convenient and practical procedure to prepare this important pharmacophore. Rearrangement precursors were also accessed from aryl halides through transitionmetal-catalyzed coupling.
- Porzelle, Achim,Woodrow, Michael D.,Tomkinson, Nicholas C. O.
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supporting information; experimental part
p. 812 - 815
(2010/04/24)
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- Benzimidazolidinone derivatives as muscarinic agents
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Benzimidazolidinone derivative compounds, which increase acetylcholine signaling or effect in the brain, and highly selective muscarinic agonists, particularly for the M1 and/or M4 receptor subtypes, pharmaceutical compositions comprising the same, as well as methods of treating psychosis using these compounds are disclosed.
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Page/Page column 18
(2010/02/06)
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- Novel compounds for use in weight loss and appetite suppression in humans
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Phenolic compounds with a phenolic molecule to which are covalently linked an oxygen-containing group, a nitrogen or another oxygen containing group, and a C1-C4 alkoxy group, obtainable from monocotyledonous plants, or by chemical synthesis, have been found to act as weight loss agents, appetite suppressants, mood enhancers and adjunctive therapy for arthritis, sleep apnea, fibromyalgia, diabetes and hyperglycemia. Additional chemical compounds of the present invention may include benzoxazinoids-cyclic hydroxyamic acids, lactams, and corresponding glucosides, which may serve as precursors to phenolic compounds. The phenolic compounds and precursors of phenolic compounds of the present invention, at concentrations suitable for human therapeutic use, may be obtained from monocotyledonous plants such as corn in their early growth states which are timely harvested for optimum yield.
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- Syntheses of 2-Hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one: A precursor of a bioactive electrophile from Gramineae
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2-Hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one (8), the hitherto undescribed free hemiacetatic aglycone of a benzoxazinoid acetal glucoside naturally occurring in wheat, has been synthesized following two pathways, independently. This cyclic hydroxamic acid methyl ester proved to be very unstable when in solution. This gives rise to the assumption that HDIBOA naturally released from its acetal glucoside is by methoxide elimination a precursor to form a multi-centered electrophile that was recently reported to be the bioactive principle of the benzoxazinoid lead.
- Escobar, Carlos A.,Kluge, Michael,Sicker, Dieter
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p. 1017 - 1020
(2007/10/03)
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- NON-INDUCED CYCLIC HYDROXAMIC ACIDS IN WHEAT DURING JUVENILE STAGE OF GROWTH
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2,4-Dihydroxy-1,4-benzoxazine -3-one glucoside (DIBOA-G) and its methoxy analogue, 2,4-dihydroxy-7-methoxy-1,4-benzoxazine-3-one glucoside (DIMBOA-G), were present in germinating wheat (Triticum aestivum); the corresponding aglycones, DIBOA and DIMBOA, appeared soon after germination.The amounts of these compounds reached a maximum 12-48 hours after germination, and then decreased to undetectable levels as the plants began autotropic growth.The time of their appearance was little affected by using seeds either sterilized or non-sterilized, by infection with pathogens and wounding with a razor blade.The concentration of DIBOA was found to be 0.2-0.3 nmol mg-1 fr. wt (0.2-0.3 nM if the density of plant tissue is assumed to be uniform and unity) and that of DIMBOA was 0.7-1.0 nmol mg-1 (0.7-1.0 nM).The aglycones retarded the germ tube growth of species of fungi at 0.3 mM.These observations suggest that the appearance of benzoxazinones is as defence compounds in the juvenile stage of growth. Anthranilic acid was incorporated into DIBOA-G and DIMBOA-G when administered to embryos isolated from pre-emerging seeds, showing that the series of compounds are generated by de novo synthesis. - Key words: Triticum aestivum; Gramineae; seedlings; hydroxamic acids; benzoxazinones; biosynthesis.
- Nakagawa, Eri,Amano, Takashi,Hirai, Nobuhiro,Iwamura, Hajime
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p. 1349 - 1354
(2007/10/02)
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- Chemical Studies on 2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one in Connection with 6-Methoxy-2-benzoxazoline, an Auxin-inhibiting Substance of Zea mays L.
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Some chemical studies on 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA, 1) and related compounds from Zea mays L. have been carried out, where DIMBOA (1) has been very rapidly converted into 6-methoxy-2-benzoxazolinone (MBOA, 2), an auxin-inhibiting substance of maize, in the presence of acetic anhydride at room temperature.Therefore, such an enzymatic acylation of N-OH group of DIMBOA (1) as in vitro presumably plays an important role on phototropism.
- Kosemura, Seiji,Yamamura, Shosuke,Anai, Toyoaki,Hasegawa, Koji
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p. 8221 - 8224
(2007/10/02)
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- Improved procedures for the preparation of 2-nitro-5-methoxyphenol and 6-methoxy-2(3H)-benzoxazolone from 3-methoxyphenol
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3-Methoxyphenol can be selectively nitrosated in propionic acid, and the resulting slurry of 2-nitroso-5-methoxyphenol can be cleanly oxidized by nitric acid to the nitro compound. An improved procedure for the preparation of 6-methoxy-2(3H)-benzoxazolone
- Maleski
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p. 343 - 348
(2007/10/02)
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- A Simple Synthesis of 2(3H)-Benzoxazolones using Phenyl Chloroformate
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2(3H)-Benzoxazolones 3 can be prepared directly from the corresponding 2-aminophenols and phenyl chloroformate.The intermediate 2-hydroxy phenylcarbamates 2 are formed easily in aqueous alcohol solvent and these are converted rapidly to product, without their isolation, using one equivalent of sodium hydroxide.The synthesis accommodates a wide variety of substituents, including the easily hydrolyzed ethyl ester.
- Maleski, Robert J.,Osborne, C. Edward,Cline, Sharon M.
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p. 1937 - 1939
(2007/10/02)
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- Analogues of the Cyclic Hydroxamic Acid 2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-one: Decomposition to Benzoxazolinones and Reaction with β-Mercaptoethanol
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Analogues of the aglucones of naturally occurring cyclic hydroxamic acids (2,4-dihydroxy-1,4-benzoxazin-3-ones) from Gramineae (Poaceae) have been synthesized by the reductive cyclization of the ring-substituted methyl α-(o-nitrophenoxy)-α-methoxyacetates, followed by demethylation of the C-2 methoxy group with BBr3 or BCl3 to reveal the 2-hydroxy group.A structure-activity series was produced by varying the substituent at C-7 on the aromatic ring .The pKa values for the hydroxamic acid and the phenol moieties were determined for each member of the C-7 series.They correlated well with ? in a linear free energy relationship (LFER) yielding values of ρ = 0.71 (with ?p) for pKa1 (the hydroxamic acid) and ρ = 1.6 (with ρm) for pKa2 (the phenol).A LFER also existed between the rate constants for the unimolecular decomposition of these hydroxamic acids to benzoxazolinones and ?+ (ρ = -1.1).The rates of hydroxamic acid reduction to lactams by β-mercaptoethanol were also investigated.It was found that only compounds with electron-rich aromatic rings and specifically an oxa functionality para to the hydroxamic acid nitrogen atom (compounds 1 and 3 - 5) had measurable rates of reduction. 1H NMR spectra recorded during this reaction in D2O buffers (pD 9), however, showed that compounds 1, 2, 6 - 9 (the only ones investigated) formed a hemithioacetal at C-2 even though only 1 has a measurable rate of reduction by the same thiol.The remarkable rate enhancement provided by an oxa functionality suggests that reduction occurs by direct attack of thiolate on the hydroxamic nitrogen of a resonance-stabilized ion pair.
- Atkinson, Jeffrey,Morand, Peter,Arnason, John T.,Niemeyer, Hermann M.,Bravo, Hector R.
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p. 1788 - 1800
(2007/10/02)
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- A Facile Synthesis of 6-Methoxy-2-oxo-2,3-dihydrobenzoxazole
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A new two-step synthesis of 6-methoxybenzoxazolin-2(3H)-one, a bioactive natural product from Gramineae, is described.The new procedure avoids disadvantages of hitherto existing methods and affords the title compound in 75percent yield from 5-methoxy-2-ni
- Sicker, Dieter
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p. 875 - 876
(2007/10/02)
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- A NEW PRODUCT FROM DECOMPOSITION OF 2,4-DIHYDROXY-7-METHOXY-1,4-BENZOXAZIN-3-ONE (DIMBOA), A HYDROXAMIC ACID FROM CEREALS
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A new product, identified as 3,4-dihydroxy-7-methoxy-1,4-benzoxazin-2-one (5) was isolated in 10percent yield from the decomposition of the title compound in dioxane.A mechanism for its formation is discussed.
- Bravo, Hector R.,Niemeyer, Hermann M.
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p. 335 - 337
(2007/10/02)
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- INTERACTION OF 2,4-DIHYDROXY-7-METHOXY-1,4-BENZOXAZIN-3-ONE (DIMBOA) WITH ALCOHOLIC SOLVENTS
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Solubilities and IR spectra of DIMBOA in alcoholic solvents showed that the carbonyl group of DIMBOA is hydrogen-bonded to the solvent.Activation parameters of DIMBOA in the same solvents sauggested that the decomposition of DIMBOA occurs through an isocyanate, in analogy with the reaction in aqueous and aprotic solvents.
- Bravo, Hector R.,Niemeyer, Hermann M.
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p. 2809 - 2812
(2007/10/02)
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- 3-(1-Imidazoyl)-6-methoxy-2-benzoxazolinone. A Byproduct of the Synthesis of 6-MBOA With 1,1'-Carbonyldiimidazole
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Previously unknown 3-(1-imidazoyl)-6-methoxy-2-benzoxazolinone was isolated as a byproduct of the synthesis of reproductive-simulant 6-methoxybenzoxazolinone (6-MBOA) with 1,1'-carbonyldiimidazole.Concomitant with byproduct formation was a 34percent reduction in the yield of the desired 6-MBOA.A brief discussion of the formation of this byproduct and maximization of the yield of 6-MBOA is included.
- Nachman, Ronald J.
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p. 279 - 280
(2007/10/02)
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- o-Hydroxyphenylureas. Intermediates in the urea fusion synthesis of 2-benzoxazolinones
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o-Hydroxyphenylureas have been identified as intermediates in the urea fusion synthesis of 2-benzoxazolinones. The pyrolysis of these intermediates represents a new alternate synthesis of the benzoxazolinone ring system.
- Nachman
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p. 1423 - 1425
(2007/10/02)
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