Copper-catalyzed three-component borylstannylation of alkynes
Regio- and stereoselective installation of boryl and stannyl moieties into a carbon-carbon triple bond of various alkynes has been achieved based on a three-component coupling reaction by using a diboron and a tin alkoxide with the aid of a copper(II) acetate-tricyclohexylphosphine complex, giving diverse vic-borylstannylalkenes in a straightforward manner. Carbon-tin and carbon-boron bonds of the resulting borylstannylation product are successively transformed into carbon-carbon bonds by a Migita-Kosugi-Stille and a Suzuki-Miyaura coupling, leading to the formation of (Z)-tamoxifen with anti-breast cancer activity. Borylstannylation: A copper-tricyclohexylphosphine complex was found to catalyse the three-component borylstannylation of alkynes with a diboron and a tin alkoxide to afford vic-borylstannylalkenes in a regio- and stereoselective manner. Synthetic utility of the resulting borylstannylation product was demonstrated by a three-step synthesis of (Z)-tamoxifen from commercially available substrates by successive Migita-Kosugi-Stille and Suzuki-Miyaura couplings (see scheme). Copyright
Takemoto, Yuki,Yoshida, Hiroto,Takaki, Ken
supporting information
p. 14841 - 14844
(2013/01/15)
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