Process for preparing isoxazole compounds
View Patent ↗A process for preparing isoxazole compounds of formula I: in which a nitroaryl of the formula (II): is contacted with an alkyl acetoacetate of the formula (III) or a salt thereof: in the presence of an activating agent and a base to provide the isoxazole compound.
1. A process for preparing an isoxazole compound of the formula (I):
the process comprising:
contacting a nitroaryl of the formula (II):
with an alkyl acetoacetate of the formula (III) or a salt thereof:
in the presence of an activating agent and a base, under conditions sufficient to provide the isoxazole compound,
wherein
Ar is phenyl, naphthyl, or biphenyl, each of which is optionally substituted with 1, 2, or 3 groups independently selected from methyl, chloro, bromo, fluoro, iodo and trifluoromethyl;
R 1 is C 1 -C 8 alkyl or cycloalkyl; and
R 2 is C 1 -C 12 alkyl, cycloalkyl, aryl, or aralkyl, each of which is optionally substituted with halogen or trifluoromethyl.
2. A process according to claim 1 wherein R 1 is C 1 -C 6 alkyl.
3. A process according to claim 1 wherein R 2 is C 1 -C 6 alkyl.
4. A process according to claim 1 wherein the alkyl acetoacetate of formula III is: ethyl acetoacetate, methyl acetoacetate, sodium ethyl acetoacetate, potassium ethyl acetoacetate, lithium ethyl acetoacetate, sodium methyl acetoacetate, potassium methyl acetoacetate, or lithium methyl acetoacetate.
5. A process according to claim 1 wherein Ar is phenyl optionally substituted with 1 or 2 halogen groups.
6. A process according to claim 1 wherein the nitroaryl compound of formula II is phenylnitromethane, chlorophenylnitromethane, or dichlorophenylnitromethane.