- Synthesis of 5-Substituted 1 H-Tetrazoles from Nitriles by Continuous Flow: Application to the Synthesis of Valsartan
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An efficient continuous flow process for the synthesis of 5-substituted 1H-tetrazoles is described. The process involves the reaction between a polymer-supported triorganotin azide and organic nitriles. The polymer-supported organotin azide, which is in situ generated with a polystyrene-supported triorganotin alkoxide and trimethylsilylazide, is immobilized in a packed bed reactor. This approach is simple, fast (it takes from 7.5 to 15 min), and guarantees a low concentration of tin residues in the products (5 ppm). The process was developed to aryl-, heteroaryl-, and also alkylnitriles and was applied for the synthesis of valsartan, an angiotensin II receptor antagonist.
- Carpentier, Florian,Felpin, Fran?ois-Xavier,Zammattio, Fran?oise,Le Grognec, Erwan
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p. 752 - 761
(2020/03/13)
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- PROCESS FOR PREPARATION OF 5-SUBSTITUTED TETRAZOLES
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The present invention is a process for preparing sterically hindered 5-substituted tetrazole, which comprises of reacting a nitrile with an organotin halide and an azide in presence of a phase transfer catalyst, in an organic solvent and a co- solvent at reflux temperature for 4 to 20 h.
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Page/Page column 15
(2010/12/18)
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- PROCESS FOR PREPARATION OF VALSARTAN INTERMEDIATE
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The present invention provides a process for preparation of a key intermediate of valsartan in a pure form and use of this intermediate for the preparation of valsartan or a pharmaceutically acceptable salt in pure form.
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- A high-throughput process for valsartan
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With the redesign of three chemical steps, the throughput of the valsartan manufacturing process could be significantly increased, and with the substitution of chlorobenzene with cyclohexane in the bromination of 4′-methyl-biphenyl-2-carbonitrile (6) to 4′bromomethyl-biphenyl-2- carbonitrile (5), halogenated solvents are no longer used in the whole valsartan production process. The alkylation of (S)-2-amino-3-methyl-butyric acid benzyl ester (8) with 4′-bromomethyl-biphenyl-2-carbonitrile (5), and the acylation of(S)-2-[(2′-cyano-biphenyl-4-ylmethyl)-amino]-3-methyl-butyric acid benzyl ester (4) to (S)-2-[(2′-cyano-biphenyl-4-ylmethyl)-pentanoyl- amino]-3-methyl-butyric acid benzyl ester (3) were thoroughly modified. In the acylation of 4 to 3, N-ethyldiisopro-pylamine was replaced by aqueous sodium hydroxide by using the conditions of the Schotten-Baumann reaction, leading to a better quality of intermediate 3. In the alkylation of 8 with 5, N-ethyldiisopropylamine was indirectly replaced by aqueous sodium hydroxide. The reaction runs under homogenous conditions with (S)-2-amino-3-methyl-butyric acid benzyl ester (8) acting as acceptor for hydrobromic acid; recycling of 8 is performed by extraction with aqueous sodium hydroxide.
- Beutler, Ulrich,Boehm, Matthias,Fuenfschilling, Peter C.,Heinz, Thomas,Mutz, Jean-Paul,Onken, Ulrich,Mueller, Martin,Zaugg, Werner
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p. 892 - 898
(2012/12/30)
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- Process for the preparation of valsartan and its intermediates
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The present invention relates to an improved process for the preparation of valsartan and its intermediates in substantially pure enantiomeric form. In particular, the present invention provides a process for preparing benzyl valsartan intermediate substantially free of organotin impurities. The valsartan produced from such benzyl valsartan intermediate requires significantly lower catalyst loading and has superior purity.
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Page/Page column 7
(2010/11/25)
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- Process for the Preparation of Valsartan and its Intermediates
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The present invention concerns a process for preparing valsartan of Formula I: comprising purifying intermediate benzyl valsartan of Formula IV by crystallizing said benzyl valsartan of lower purity from a first solvent which is a ternary mixture comprising a hydrophilic solvent, a non-polar protic solvent and water; recovering benzyl valsartan from said ternary mixture followed by crystallizing benzyl valsartan from a second solvent comprising a non-polar aprotic solvent or polar aprotic solvent or their mixture; and recovering benzyl valsartan substantially free of organotin impurity; and converting said benzyl valsartan of into valsartan
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Page/Page column 3; 8-9
(2008/06/13)
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- ACYL COMPOUNDS
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Compounds of the formula STR1 in which R 1 is an aliphatic hydrocarbon radical which is unsubstituted or substituted by halogen or hydroxyl, or a cycloaliphatic or araliphatic hydrocarbon radical; X 1 is CO, SO 2, or--O--C(=O)--with the carbon atom of the carbonyl group being attached to the nitrogen atom shown in formula I; X 2 is a divalent aliphatic hydrocarbon radical which is unsubstituted or substituted by hydroxyl, carboxyl, amino, guanidino or a cycloaliphatic or aromatic radical, or is a divalent cycloaliphatic hydrocarbon radical, it being possible for a carbon atom of the aliphatic hydrocarbon radical to be additionally bridged by a divalent aliphatic hydrocarbon radical; R. sub.2 is carboxyl which, if desired, is esterified or amidated, substituted or unsubstituted amino, formyl which, if desired, is acetalized, 1H-tetrazol-5-yl, pyridyl, hydroxyl which, if desired, is etherified, S(O) m--R where m is 0, 1 or 2 and R is hydrogen or an aliphatic hydrocarbon radical, alkanoyl, unsubstituted or N-substituted sulfamoyl or PO n H 2 where n is 2 or 3; X 3 is a divalent aliphatic hydrocarbon; R 3 is carboxyl, 5-tetrazolyl, SO. sub.3 H, PO. sub.2 H 2, PO 3 H 2 or haloalkylsulfamoyl; and the rings A and B independently of one another are substituted or unsubstituted; in free form or in salt form, can be prepared in a manner known per se and can be used, for example, as medicament active ingredients.
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