Enones conjugate borylations

Scheme 2.31 Copper-catalysed asymmetric borylation of conjugated enones...

Analogously, copper(I) salts cleave diboron compounds [e.g., bis(pinacolato)diboron] to give, in the presence of an a,/3-enone, the corresponding conjugate boration product (eq 113). In contrast to the silylation procedure, reactions can be run at room temperature both on cyclic and acyclic enones. Subsequent oxidation of the borylated ketone provides the /3-hydroxyketone. 

The first Cu-catalyzed asymmetric borylative cyclization reaction between cyclohexadienone-containing 1,6-enynes and B2pin2 was established to afford an optically pure d5-hydrobenzo[l ]furan framework bearing alkenylboronate and enone substructures through a tandem process of selective P-borylation of the propargylic ether and subsequent enantioselective conjugate addition to cyclohexadienone (13JA11700). 

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