Synthesis of Alkyl and Aryl Boronate Esters via CeO 2 -Catalyzed Borylation of Alkyl and Aryl Electrophiles Including Alkyl Chlorides.

A recyclable protocol using a CeO 2 -nanorod catalyst for borylation of alkyl halides with B 2 pin 2 (pin = OCMe 2 CMe 2 O) is reported. A wide range of synthetically useful alkyl boronate esters are readily obtained from primary and secondary alkyl electrophiles, including unactivated alkyl chlorides, demonstrating broad utility and functional group tolerance. Preliminary investigation revealed an involvement of in situ formed catalytically active boryl species. The catalyst can be reused for up to six runs without appreciable loss in activity. In addition, we have demonstrated the use of this recyclable catalyst for the borylation of aryl halides with B 2 pin 2 , providing valuable aryl boronate esters under neat conditions.