Method for the production of 1-substituted 5-hydroxypyrazoles

Details Method for the production of 1-substituted 5-hydroxypyrazoles Method for the production of 1-substituted 5-hydroxypyrazoles

C - Chemistry, Metallurgy

07

D

C07D 231/20 (2006.01)

Patent

CA 2351425

The invention relates to a method for the production of 1-substituted 5- hydroxypyrazoles of formula (I) wherein R1 is C1-C6-alkyl, C2-C6-alkenyl, C2- C6-alkinyl, C3-C6-cycloalkyl or C1-C4-alkoxy, whereby these groups can be substituted by halogen, C1-C4-alkoxy, phenoxy, C1-C6-alkoxycarbonyl, C1-C6- alkylthiocarbonyl or a cyclic ring system with 3-14 ring atoms, by reacting a) an alkylvinylether of general formula (III) wherein R2 is C1-C6-alkyl or C3-C6- cycloalkyl, with phosgene (IVa), "diphosgene" (IVb) or "triphosgene" (IVc) to form acid chlorides of formula (V), b) transforming said acid chlorides by eliminating hydrogen chloride into the corresponding 3-alkoxyacrylic acid chloride of formula (VI) and c) reacting said acid chloride with hydrazines of formula (VII) wherein R1 has the above cited meaning, to form 5- hydroxypyrazoles of formula (I).

Procédé de préparation de 5-hydroxypyrazoles substitués en position 1, de formule (I) dans laquelle R?1¿ représente alkyle C¿1?-C¿6?, alcényle C¿2?-C¿6?, alcinyle C¿2?-C¿6?, cycloalkyle C¿3?-C¿6? ou alcoxy C¿1?-C¿4?, ces groupes pouvant être substitués par halogène, alcoxy C¿1?-C¿4?, phénoxy, alcoxycarbonyle C¿1?-C¿6?, alkylthiocarbonyle C¿1?-C¿6? ou un système de noyau cyclique ayant 3 à 14 atomes sur le noyau, qui consiste à faire réagir (a) un alkylvinyléther de formule générale (III), dans laquelle R?2¿ représente alkyle C¿1?-C¿6? ou cycloalkyle C¿3?-C¿6?, avec du phosgène (IVa), du "diphosgène" (IVb) ou du "triphosgène" (IVc) pour obtenir des chlorures d'acide de formule (V), (b) à transformer ces chlorures d'acides par élimination du gaz chlorhydrique en chlorure d'acide 3-alcoxyacrylique de formule (VI) et (c) à faire réagir ce chlorure avec des hydrazines de formule (VII) dans laquelle R?1¿ est tel que défini ci-dessus, pour obtenir des 5-hydroxypyrazoles de formule (I).

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