Widely Exploited, Yet Unreported: Regiocontrolled Synthesis and the Suzuki-Miyaura Reactions of Bromooxazole Building Blocks

An approach to synthesis of 2-, 4-, and 5-bromooxazoles is described. The method was optimized, and its scope was extended to all three isomeric parents, as well as various alkyl- and aryl-substituted bromooxazoles. It was found that direct regiocontrolled lithiation followed by reaction with electrophilic bromine source was common for all substrates and led exclusively to the target substituted 2-, 4- and 5-bromooxazoles on multigram scale. The utility of the multipurpose building blocks obtained in this work was demonstrated in the Suzuki-Miyaura cross-coupling reaction under parallel synthesis conditions.