Selective Benzylic CH‐Borylations by Tandem Cobalt Catalysis

Abstract

Metal-catalyzed C À Ha ctivations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre-functionalized substrates and minimizew aste generation. Great challenges reside in the control of selectivities,the utilization of unbiased hydrocarbons,a nd the operation of atom-economical dehydrocoupling mechanisms.Anespecially mild borylation of benzylic CH bonds was developed with the ligand-free pre-catalyst Co[N(SiMe 3 ) 2 ] 2 and the bench-stable and inexpensive borylation reagent B 2 pin 2 that produces H 2 as the only by-product. Af ull set of kinetic, spectroscopic,a nd preparative mechanistic studies are indicative of at andem catalysis mechanism of CH-borylation and dehydrocoupling via molecular Co I catalysts.

The recent advances in cobalt-catalyzed C(sp3)–H functionalization reactions

“…In 2022, Wangelin and co-workers established the cobalt-catalyzed undirected C(sp 3 )–H borylation at the benzylic position (Scheme 42). 43 The advantages of this reaction include inexpensive catalysts, mild conditions, broad substrate scope, high product selectivity, and effective use of a borane reagent. The authors investigated the reaction using various kinds of cobalt catalysts such as Co(OAc) 2 , Co(hmds) 2 , CoBr 2 , etc ., among which Co(hmds) 2 worked more effectively.…”