US 12,410,145 B2
Efficient process for making 6-carboxy benzoxazole derivatives
Simon Peter Curran, Frankfield (IE); and Padraig Mary O'Neill, Crosshaven (IE)
Assigned to Pfizer Inc., New York, NY (US)
Appl. No. 17/757,740
Filed by Pfizer Ireland Pharmaceuticals, New York, NY (US)
PCT Filed Dec. 16, 2020, PCT No. PCT/IB2020/062040
§ 371(c)(1), (2) Date Jun. 20, 2022,
PCT Pub. No. WO2021/124158, PCT Pub. Date Jun. 24, 2021.
Claims priority of provisional application 63/120,426, filed on Dec. 2, 2020.
Claims priority of provisional application 62/951,691, filed on Dec. 20, 2019.
Prior Publication US 2023/0090609 A1, Mar. 23, 2023
Int. Cl. C07D 263/57 (2006.01); C07D 493/18 (2006.01)
CPC C07D 263/57 (2013.01) [C07D 493/18 (2013.01)] 33 Claims
 
1. A process for preparing a 6-Carboxy-2-(3,5-dichlorophenyl)benzoxazole compound of Formula I

OG Complex Work Unit Chemistry
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

OG Complex Work Unit Chemistry
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.