Cobalt-Catalyzed Cross-Dehydrogenative C(sp2)−C(sp3) Coupling of Oxazole/Thiazole with Ether or Cycloalkane
Direct C5-alkylation of oxazole/thiazole with ether or cycloalkane has been achieved through a cobalt-catalyzed cross-dehydrogenative coupling (CDC) process in moderate to good yields. This transformation represents the first C(sp2)−C(sp3) cross-coupling at the C5-position of the oxazole/thiazole via double C−H bond cleavages. Various functional groups on oxazole/thiazole substrates, as well as water and air, are well-tolerated with this concise and practical protocol, constituting straightforward access to heterocycles with great medicinal significance. A preliminary mechanism involving a radical process has also been proposed.