Regioselective Functionalization of the Oxazole Scaffold Using TMP-Bases of Mg and Zn

A general method for the synthesis of 2,4,5-trisubstituted oxazoles has been developed. Starting from commercially available oxazole, successive metalations using TMPMgCl center dot LiCl or TMPZnCl center dot LiCl led to the corresponding magnesiated or zincated species which were stable toward ring fragmentation. Furthermore, they readily reacted with various electrophiles, such as aryl and allylic halides, acid chlorides, TMSCl, and TMS-CN, providing highly functionalized oxazoles.