- Taming Ambident Triazole Anions: Regioselective Ion Pairing Catalyzes Direct N-Alkylation with Atypical Regioselectivity
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Controlling the regioselectivity of ambident nucleophiles toward alkylating agents is a fundamental problem in heterocyclic chemistry. Unsubstituted triazoles are particularly challenging, often requiring inefficient stepwise protection-deprotection strategies and prefunctionalization protocols. Herein we report on the alkylation of archetypal ambident 1,2,4-triazole, 1,2,3-triazole, and their anions, analyzed by in situ 1H/19F NMR, kinetic modeling, diffusion-ordered NMR spectroscopy, X-ray crystallography, highly correlated coupled-cluster computations [CCSD(T)-F12, DF-LCCSD(T)-F12, DLPNO-CCSD(T)], and Marcus theory. The resulting mechanistic insights allow design of an organocatalytic methodology for ambident control in the direct N-alkylation of unsubstituted triazole anions. Amidinium and guanidinium receptors are shown to act as strongly coordinating phase-transfer organocatalysts, shuttling triazolate anions into solution. The intimate ion pairs formed in solution retain the reactivity of liberated triazole anions but, by virtue of highly regioselective ion pairing, exhibit alkylation selectivities that are completely inverted (1,2,4-triazole) or substantially enhanced (1,2,3-triazole) compared to the parent anions. The methodology allows direct access to 4-alkyl-1,2,4-triazoles (rr up to 94:6) and 1-alkyl-1,2,3-triazoles (rr up to 99:1) in one step. Regioselective ion pairing acts in effect as a noncovalent in situ protection mechanism, a concept that may have broader application in the control of ambident systems.
- Dale, Harvey J.A.,Hodges, George R.,Lloyd-Jones, Guy C.
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p. 7181 - 7193
(2019/05/10)
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- Preparation method of rizatriptan benzoate intermediate
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The invention relates to a preparation method of a rizatriptan benzoate intermediate. The preparation method of the rizatriptan benzoate intermediate comprises the following steps of: (1) adding a solvent, a basic catalyst, polyethylene glycol and (1H)-1,2,4-triazole for uniform mixing under a stirring condition to form a solution, and (2) adding p-nitrobenzyl halide into the solution prepared instep (1) under a high-speed stirring condition, and performing reaction at a certain temperature to form 1-(4-nitrophenyl) methyl-1,2,4-triazole. According to the preparation method of the rizatriptanbenzoate intermediate, the addition of a certain amount of polyethylene glycol into a solvent can promote a reaction course and greatly increase a product yield, so that the preparation method achieves the purposes of higher yield, higher efficiency and low cost.
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Paragraph 0019-0024; 0027-0031
(2018/07/06)
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- Liquid ammonia as a dipolar aprotic solvent for aliphatic nucleophilic substitution reactions
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The rate constants for the reactions of a variety of nucleophiles reacting with substituted benzyl chlorides in liquid ammonia (LNH3) have been determined. To fully interpret the associated linear free-energy relationships, the ionization constants of phenols ions in liquid ammonia were obtained using UV spectra. These equilibrium constants are the product of those for ion-pair formation and dissociation to the free ions, which can be separated by evaluating the effect of added ammonium ions. There is a linear relationship between the pKa of phenols in liquid ammonia and those in water of slope 1.68. Aminium ions exist in their unprotonated free base form in liquid ammonia and their ionization constants could not be determined by NMR. The rates of solvolysis of substituted benzyl chlorides in liquid ammonia at 25 °C show a Hammett ρ of zero, having little or no dependence upon ring substituents, which is in stark contrast with the hydrolysis rates of substituted benzyl halides in water, which vary 107 fold. The rate of substitution of benzyl chloride by substituted phenoxide ions is first order in the concentration of the nucleophile indicative of a SN2 process, and the dependence of the rate constants on the pKa of the phenol in liquid ammonia generates a Bronsted βnuc = 0.40. Contrary to the solvolysis reaction, the reaction of phenoxide ion with 4-substituted benzyl chlorides gives a Hammett ρ = 1.1, excluding the 4-methoxy derivative, which shows the normal positive deviation. The second order rate constants for the substitution of benzyl chlorides by neutral and anionic amines show a single Bronsted βnuc = 0.21 (based on the aqueous pKa of amine), but their dependence on the substituent in substituted benzyl chlorides varies with a Hammett ρ of 0 for neutral amines, similar to that seen for solvolysis, whereas that for amine anions is 0.93, similar to that seen for phenoxide ion.(Figure Presented)
- Ji, Pengju,Atherton, John,Page, Michael I.
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supporting information; scheme or table
p. 1425 - 1435
(2011/04/23)
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- PROCESS FOR THE LARGE SCALE PRODUCTION OF RIZATRIPTAN BENZOATE
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The present invention provides a method for preparing pure Rizatriptan benzoate having purity more than 99.5% and dimer impurity less than 0.1% comprises, i) Condensation of 1,2,4-Triazole with 4-Nitro benzyl bromide to yield l-(4-nitrophenyl) methyl-1,2,4- triazole ii) Reducing the l-(4-nitrophenyl) methyl-1,2,4-triazole to give l-(4- aminophenyl) methyl-1,2,4-triazole iii) Converting l-(4-aminophenyl) methyl-1,2,4-triazole to l-(4-hydrazinophenyl) methyl-1,2,4-triazole hydrochloride iv) Condensing the hydrazine derivative with 4-(Dimethylamino) butanal diethylacetal to get Rizatriptan and v) Salification of Rizatriptan to Rizatriptan benzoate.
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Page/Page column 4; 8
(2008/06/13)
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- IMPROVED PROCESS FOR THE PREPARATION OF RIZATRIPTAN BENZOATE
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Present invention discloses an improved and commercially viable process for the preparation of rizatriptan benzoate of formula (I). According to the present process the hydrazone intermediate derived from the phenylhydrazine of formula- (III) and 4- dimethylaminobutyraldehyde diethyl acetal is gradually heated to 60-70 °C in aqueous sulfuric acid medium and maintained for 3-4hr to get rizatriptan with less dimeric impurity of formula (X). The resultant rizatriptan is isolated and converted into the pharmaceutically acceptable benzoate salt. Present process produces less percentage of dimeric (less than 3 %) or polymeric impurities compared to the prior art process and more yield of rizatriptan. Rizatriptan benzoate produced according to the present process has more than 99.5 % purity with less than 0.1% dimeric impurity of formula (X) by HPLC. Rizatriptan benzoate is useful for the treatment of migraine.
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- IMIDAZOQUINOLINES AS LIPID KINASE INHIBITORS
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The invention relates to novel organic compounds of formula (I) processes for the preparation thereof, the application thereof in a process for the treatment of the human or animal body, the use thereof - alone or in combination with one or more other pharmaceutically active compounds - for the treatment of an inflammatory or obstructive airway disease, such as asthma, disorders commonly occurring in connection with transplantation, or a proliferative disease, such as a tumor disease.
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Page/Page column 92
(2008/06/13)
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- Substituted indolines which inhibit receptor tyrosine kinases
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Indolinones of the formula having an inhibitory effect on receptor tyrosine kinases and cyclin/CDK complexes, as well as on the proliferation of endothelial cells and various tumor cells. Exemplary are: (a) 3-Z-[1-(4-(piperidin-1-yl-methyl)-anilino)-1-phenyl-methylene]-6-ethoxycarbonyl-2-indolinone, (b) 3-Z-[(1-(4-(piperidin-1-yl-methyl)-anilino)-1-phenyl-methylene]-6-carbamoyl-2-indolinone, and (c) 3-Z-[1-(4-(piperidin-1-yl-methyl)-anilino)-1-phenyl-methylene]-6-metboxycarbonyl-2-indolinone.
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Page column 41
(2008/06/13)
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- An investigation into the alkylation of 1,2,4-triazole
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The alkylation of 1,2,4-triazole with 4-nitrobenzyl halides and a variety of bases afforded the 1- and 4-alkylated isomers with a consistent regioselectivity of 90:10. Previously reported regiospecific alkylations of 1,2,4-triazole were re-examined and the quoted isomer ratios were shown to depend on the isolation procedure. The use of DBU as base in the alkylation of 1,2,4-triazole allows for a convenient and high yielding synthesis of 1- substituted-1,2,4-triazoles. (C) 2000 Elsevier Science Ltd.
- Bulger, Paul G.,Cottrell, Ian F.,Cowden, Cameron J.,Davies, Antony J.,Dolling, Ulf-H.
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p. 1297 - 1301
(2007/10/03)
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- Imidazole, Triazole and tetrazole derivatives
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Imidazole, triazole and tetrazole derivatives of formula (I) are selective agonists of 5-HT1 -like receptors and are therefore useful in the treatment of clinical conditions, in particular migraine and associated disorders, for which a selective agonist of these receptors is indicated, wherein the broken circle represents two non-adjacent double bonds in any position in the five-membered ring; two, three or four of V, W, X, Y and Z represent nitrogen and the remainder represent carbon provided that, when two of V, W, X, Y and Z represent nitrogen and the remainder represent carbon, then the said nitrogen atoms are in non-adjacent positions within the five-membered ring; E represents a bond or a straight or branched alkylene chain containing from 1 to 4 carbon atoms; F represents a group of formula (a); U represents nitrogen or C--R2 ; B represents oxygen, sulphur or N--R3 ; R1 represents a group of formula (i), (ii) or (iii).
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- Process for preparing indole derivatives containing a 1,2,4-triazol-1-yl substituent
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A process for preparing tryptamine derivatives and related compounds having a 1,2,4-triazol-1-yl moiety within the molecule comprises reacting 4-amino-1,2,4-triazol with a nitrobenzene derivative containing a readily displaceable group; deaminating the aminotriazolium salt thereby obtained by treatment with nitrous acid followed by neutralisation; reducing the triazolyl-nitrobenzene derivative thereby obtained by transfer hydrogenation; treating the triazolyl-aniline derivative thereby obtained with nitrous acid and then with an alkali metal sulphate, followed by acidification; and subsequently reacting the triazolyl-hydrazine derivative thereby obtained in situ with a suitable carbonyl compound, to obtain the required triazolyl-indole derivative.
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- Sulphate salt of a substituted triazole, pharmaceutical compositions thereof, and their use in therapy
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The sulphate salt of N,N-dimethyl-2-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine is a selective agonist of 5-HT 1 -like receptors and is therefore useful in the treatment of clinical conditions, in particular migraine and associated disorders, for which a selective agonist of these receptors is indicated.
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- Synthesis and serotonergic activity of N,N-dimethyl-2-[5-(1,2,4-triazol- 1-ylmethyl)-1H-indol-3-yl]ethylamine and analogues: Potent agonists for 5- HT(1D) receptors
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The synthesis and the 5-HT receptor activity of a novel series of N,N- dimethyltryptamines substituted in the 5-position with an imidazole, triazole, or tetrazole ring are described. The objective of this work was to identify potent and selective 5-HT(1D) receptor agonists with high oral bioavailability and low central nervous system penetration. Compounds have been prepared in which the azole ring is attached through either nitrogen or carbon to the indole. Conjugated and methylene-bridged derivatives have been studied (n = 0 or 1). Substitution of the azole ring has been explored either α or β to the point of attachment to indole. In a series of N-linked azoles (X = N), simple unsubstituted compounds have high affinity and selectivity for 5-HT(1D) receptors. It is proposed that for good affinity and selectivity a hydrogen bond acceptor interaction with the 5-HT(1D) receptor, through a β-nitrogen in the azole ring, is required. In a series of C-linked triazoles and tetrazoles (X = C), optimal affinity and selectivity for the 5-HT(1D) receptor was observed when the azole ring is substituted at the 1-position with a methyl or ethyl group. This study has led to the discovery of the 1,2,4-triazole 10a (MK-462) as a potent and selective 5-HT(1D) receptor agonist which has high oral bioavailability and rapid oral absorption. The in vitro activity and the preliminary pharmacokinetics of compounds in this series are presented.
- Street,Baker,Davey,Guiblin,Jelley,Reeve,Routledge,Sternfeld,Watt,Beer,Middlemiss,Noble,Stanton,Scholey,Hargreaves,Sohal,Graham,Matassa
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p. 1799 - 1810
(2007/10/02)
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- Triazole containing indole derivatives
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A class of substituted imidazole, triazole and tetrazole derivatives are selective agonists of 5-HT 1 -like receptors and are therefore useful in the treatment of clinical conditions, in particular migraine and associated disorders, for which a selective agonist of these receptors is indicated.
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- Synthesis and antimycotic activity of new (1H-1,2,4-triazol-1-ylmethyl)benzeneamine derivatives
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The synthesis and antimycotic activity of new triazole derivatives are reported. Microbiological assays show a good effectiveness against Aspergillus flavus, A. parassiticus and Fusarium solani. The same structures are completely inactive against Microsporium gypseum, Penicillum sp. and Candida albicans.
- Scalzo,Biava,Cerreto,Porretta,Mercantini,Fanelli
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p. 537 - 540
(2007/10/02)
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