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US 12,410,145 B2Granted
Efficient process for making 6-carboxy benzoxazole derivatives
AssigneePfizer Inc.
InventorsSimon Peter Curran, Padraig Mary O'Neill
Life of this patent
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Abstract
The present invention is directed to an efficient process for preparing benzoxazole derivatives comprising the step of reacting a 4-Amino-3-hydroxybenzoic acid compound of Formula III with a 3,5-Dichlorophenyl ortho ester compound of Formula II to provide the compound of Formula I wherein R1, R2a, R2b and R2c are as described herein.
Claims33
A process for preparing a 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole compound of Formula I
- the process comprising reacting a 4-Amino-3-hydroxybenzoic acid compound of Formula III with a 3,5-Dichlorophenyl ortho ester compound of Formula II in the presence of an acid catalyst in a solvent to provide the compound of Formula I
- wherein R1 is hydrogen or a carboxy protecting group, and R2a, R2b and R2c are each independently C1-C6alkyl or any two of R2a, R2b and R2c taken together are a C1-C6alkanediyl or R2a, R2b and R2c taken together are a C3-C10alkanetriyl;
- and the solvent is selected from the group consisting of methanol, ethanolisopropanol, n-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, t-butyl methyl ether, anisole, ethyl acetate, chloroform, chlorobenzene, heptane, cyclohexane, toluene, acetonitrile and 1,2-dimethoxyethane.
A process for preparing 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole of Formula Ia
- the process comprising reacting 4-Amino-3-hydroxybenzoic acid of Formula IIIa with a 3,5-Dichlorophenyl ortho ester compound of Formula II in the presence of an acid catalyst in a solvent to provide 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole of Formula Ia
- wherein R2a, R2b and R2c are each independently C1-C6alkyl or any two of R2a, R2b and R2c taken together are a C1-C6alkanediyl or R2a, R2b and R2c taken together are a C3-C10alkanetriyl;
- and the solvent is selected from the group consisting of methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, t-butyl methyl ether, anisole, ethyl acetate, chloroform, chlorobenzene, heptane, cyclohexane, toluene, acetonitrile and 1,2-dimethoxyethane.
A process for preparing 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole of Formula Ia
- the process comprising reacting about one molar equivalent of 4-Amino-3-hydroxybenzoic acid of Formula IIIa with about one molar equivalent of the 3,5-Dichlorophenyl ortho ester compound of Formula IIa in a solvent to provide 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole of Formula Ia
Dependencies are inferred from the claim text.