- Preparation of triazoles by organometallic addition to ketones and intermediates therefor
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A process for the preparation of a compound of the formula: or an acid addition or base salt thereof, wherein R is phenyl optionally substituted by 1 to 3 substituents each independently selected from halo and trifluoromethyl; R1 is C1-C6 alkyl; and “Het” is pyrimidinyl optionally substituted by 1 to 3 substituents each independently selected from C1-C4 alkyl, C1-C4 alkoxy, halo, oxo, benzyl and benzyloxy, comprising reacting a compound of the formula: with a compound of the formula wherein X is chloro, bromo or iodo, the reaction taking place in the presence of zinc; at least one of iodine or a Lewis acid; and an aprotic organic solvent: optionally further reacting the resulting compound with an acid or base to form the corresponding acid addition or base salt thereof.
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- Process development of voriconazole: A novel broad-spectrum triazole antifungal agent
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In the synthesis of (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoro-4-pyrimidinyl)-1-(1H-1,2,4-triazol-1- yl)-2-butanol (voriconazole), the relative stereochemistry is set in the addition of a 4-(1-metalloethyl)-5-fluoropyrimidine derivative to 1-(2,4-difluorophenyl)-2-(1H-1,2,4-triazol-1-yl)-1-ethanone. The diastereo-control of this reaction has been examined by variation of pyrimidine substitution pattern and by changes in the metalation and reaction conditions. Excellent diastereoselection (12: 1) is obtained using an organozinc derivative of 6-(1-bromoethyl)-4-chloro-5-fluoropyrimidine. After removal of the chlorine from the pyrimidine ring, the absolute stereochemistry of voriconazole is established via a diastereomeric salt resolution process using (1R)-10-camphorsulfonic acid. Synthetic routes to the pyrimidine partner have also been evaluated. The initial six-step development route from 5-fluorouracil has been superseded by a four-step synthesis involving fluorination of methyl 3-oxopentanoate and cyclisation with formamidine acetate.
- Butters, Mike,Ebbs, Julie,Green, Stuart P.,MacRae, Julie,Morland, Matthew C.,Murtiashaw, Charles W.,Pettman, Alan J.
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