Copper catalysts hydroboration

Catalytic hydroboration of terminal allg nes with B2(pin)2 is achieved by employing a copper catalyst. Products are obtained regioselectively by employing a suitable NHC ligand (Scheme 15.34). A bull bidentate phosphine ligand is effective for regioselective hydroboration of aryl-substituted... 

Following advances made in reduction reactions (vide supra), hydroboration and diboration have been the subject of intense investigation with NHC-Cu catalysts. Early work by Sadighi revealed that [(ICy)Cu(Ot-Bu)] efficiently catalyzed the 1,2-diboration of aldehydes. Mechanistic studies permitted to rationalize a number of features of this reaction and notably ruled out a possible oxidative addition pathway to favour c-activation of the diboron reagent by the copper centre. [(ICy)Cu(Ot-Bu)] was also used for the diaster-eoselective diboration—in fact, hydroboration after work-up—of sulfinyl aldimines. ... 

Somewhat related to cross-coupling reactions, the carbomagnesiation of terminal alkenes was shown to proceed efficiently in the presence of [(IMes)AgCl] and 1,2-dibromoethane, which was used as an oxidant. The hydroboration of terminal alkynes was also achieved using [(NHC)Ag] catalysts, and with higher regioselectivity compared to copper catalysis conditions. 

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