- A practical in situ generation of the schwartz reagent. reduction of tertiary amides to aldehydes and hydrozirconation
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A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
- Zhao, Yigang,Snieckus, Victor
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supporting information
p. 390 - 393
(2014/04/03)
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- Chemoselective zinc/HCl reduction of halogenated β-nitrostyrenes: Synthesis of halogenated dopamine analogues
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A detailed account regarding the synthesis of 2- and 5-halogenated dopamine is given. The key step is a chemoselective reduction of a nitrostyrene by Zn/HCl at 0 °C. These conditions represent a simple, low-cost alternative to reduction by water-sensitive hydride donors and two-step procedures. Under these conditions, aryl fluoride, chloride, and bromide groups are stable. However, iodine undergoes significant reductive dehalogenation.
- Maresh, Justin J.,Ralko, Arthur A.,Speltz, Tom E.,Burke, James L.,Murphy, Casey M.,Gaskell, Zachary,Girel, Joann K.,Terranova, Erin,Richtscheidt, Conrad,Krzeszowiec, Mark
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supporting information
p. 2891 - 2894
(2015/02/02)
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- Schwartz Reagents: Methods of In Situ Generation and Use
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Embodiments of the invention provide a method of using Schwartz Reagent, Cp2Zr(H)Cl, without accumulating or isolating it. Methods provide mixtures of Cp2ZrCl2, reductants that selectively reduce Cp2ZrCl2, and substrates. After reaction of Cp2ZrCl2 and the reductant, an intermediate reduction product is formed, apparently Schwartz Reagent. The in situ Schwartz Reagent then selectively reduces certain functional groups on the substrate. Substrates include tertiary amides, tertiary benzamides, aryl O-carbamates, and heteroaryl N-carbamates, which are reduced to aldehydes, benzaldehydes, aromatic alcohols, and heteroaromatics, respectively. Compared to prior methods, reagents are inexpensive and stable, reaction times are short, and reaction temperature in certain cases is conveniently room temperature. It has been estimated that using the in situ method described herein instead of synthesized or commercially obtained Schwartz Reagent provides a 50% reduction in cost.
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Page/Page column 7; 11
(2010/06/19)
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- Synthesis of N-(2-chloro-3,4-dimethoxybenzylideneamino)guanidinium acetate [α-14C]
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14C-Labelled N-(2-chloro-3,4-dimethoxybenzylideneamino)guanidinium acetate has been synthesized as a part of a four-step procedure which involved decarboxylation of 2-chloro-3,4-dimethoxybenzoic acid by Pb(OAc)4 to give 2-chloro-3,4-dimethoxy-1-iodobenzene, followed by a selective lithiation at the iodine position and electrophilic substitution with N,N-dimethylformamide [α-14C] and final reaction with aminoguanidine bicarbonate. The specific activity was 59 mCi/mmol and the overall yield 49%. Copyright
- Almeida, Maria,Boman, Arne,Lundstedt, Torbjrn
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p. 371 - 377
(2007/10/03)
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- Aryl-substituted cycloalkanes and cycloalkenes and herbicidal use thereof
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Disclosed are herbicidal aryl substituted cycloalkyl and aryl substituted cycloalkenyl compounds, herbicidal compositions, and herbicidal use of the compounds and compositions. The aryl substituent is selected from substituted phenyl, unsubstituted or substituted five-membered heterocycle, and unsubstituted or substituted six-membered heterocycle.
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- Solid oral preparation containing a pyrrolidine derivative with a catechol group
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An oral solid preparation comprising an organic acid or its salt and a catechol compound. The catechol compound is, for example, a pyrrolidine derivative having a catechol group of the following general formula (I). It exhibits an improved absorbability in vivo. STR1
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- Chemical processes for 2-(2-halo-3,4-dimethoxybenzyl)-5-(4-methoxyphenyl)oxazolidines
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New intermediates, namely 2-(2-halo-3,4-dimethoxybenzyl)-5-(4-methoxyphenyl)-oxazolidines, are prepared by a synthetic sequence which uses a Darzen's reaction in a homogeneous solvent system.
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- Synthesis and Renal Vasodilator Activity of 2-Chlorodopamine and N-Substituted Derivatives
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A four-step synthesis of 2-chlorodopamine (2b) is presented as well as methods for the syntheses of the N-methyl, ethyl, and n-propyl analogues (2c-e).Compounds 2b and 2c were essentially equipotent to dopamine for increasing renal blood flow in anesthesized dogs that had been treated with the α-adrenergic antagonist phenoxybenzamine.The increases in renal blood flow were blocked by the DA1 antagonist (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine.Compounds 2d and 2e were significantly less potent than dopamine in the same model; the increases in renal blood flow were attenuated by propanolol and blocked by a combination of propanolol and (R)-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine.The significance of an o-chloro substituent on dopamine analogues for the activation of the DA1 receptor is briefly discussed.
- McCarthy, James R.,McCowan, Jefferson,Zimmerman, Mark B.,Wenger, Marcia A.,Emmert, Lee W.
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p. 1586 - 1590
(2007/10/02)
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- 6-HALO-7,8-DIHYDROXY-1-PHENYL-2,3,4,5-TETRAHYDRO-1H-3-BENZAZEPINES
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7,8-Dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepines having a halo substituent at the 6-position have potent dopaminergic activity. The 6-chloro congeners are most active.
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- 6-HALO-3-LOWER ALKYL-7,8-DIHYDROXY-1-PHENYL-2,3,4,5-TETRAHYDRO-1H-3-BENZAZEPINES
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6-Halo-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepines whose structures have a lower alkyl substituted at the 3 or N-position have potent and often specific anti-Parkinsonism activity by means of their central dopaminergic effect. The lead compound of the series is 6-chloro-3-methyl-1-phenyl-7,8-dihydroxy-2,3,4,5-tetrahydro-1H-3-benzazepin e as the base or its salts such as the hydrochloride, hydrobromide or methane sulfonate.
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- Substituted 1-alkylthiophenyl-2,3,4,5-tetrahydro-1H-3-benzazepine compounds
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A group of 1-phenyl-1H-3-benzazepines whose structures are characterized by having a functional thio containing group on the 1-phenyl moiety and which have pronounced peripheral and diminished central dopaminergic activity. This activity is manifested in an anti-hypertensive effect in humans. Particular species of this group include 6-chloro-7,8-dihydroxy-1-p-methylthiophenyl-2,3,4,5-tetrahydro-1H-3-benzazepine and its derivatives which have dopaminergic activity.
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- 2,3,4,5-TETRAHYDRO-1H-3-BENZAZEPINE-7,8-DIONES
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Novel benzazepine derivatives having central and peripheral dopaminergic activity useful in treating Parkinson's and cardiovascular diseases. The compounds have additional use as intermediates for the synthesis of other benzazepines with similar useful properties. The 1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-dione derivatives are particularly useful.
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