4-Bromomethyl-2-chlorooxazole––a versatile oxazole cross-coupling unit for the synthesis of 2,4-disubstituted oxazoles

The synthesis of the novel oxazole building block, 4-bromomethyl-2-chlorooxazole, and its palladium-catalysed cross-coupling reactions to make a range of 2,4-disubstituted oxazoles, is described. Selectivity for the 4-bromomethyl position is observed, with Stille coupling effected in good to excellent yields, or Suzuki coupling in moderate yields, to provide a range of 4-substituted-2-chlorooxazoles. Subsequent coupling at the 2-chloro-position can be achieved through either Stille or Suzuki reactions in excellent yields.