Approach to the Synthesis of gem -Thiolated Alkylboronates via Cobalt-Catalyzed Diboration of Aldehydes.

A new method has been developed for the sequential gem -thioborylation of readily available aldehydes via the cobalt-catalyzed diboration reaction. The N -heterocyclic carbene (NHC)-cobalt complex has been used as a catalyst for the diboration of aldehydes to generate α-oxyl boronic esters, which react with lithium thiolates to form a tetracoordinate boronate species, which undergoes 1,2-metalate rearrangement in the presence of trifluoroacetic anhydride. The stepwise functionalization of the boryl and thiol moiety of the products enriches the chemical toolbox of diverse organic synthesis.