Enantioselective total syntheses of (-)-taiwaniaquinone H and (-)-taiwaniaquinol B by iridium-catalyzed borylation and palladium-catalyzed asymmetric α-arylation.
We report a concise, enantioselective total synthesis of (-)-taiwaniaquinone H and the first enantioselective total synthesis of (-)-taiwaniaquinol B by a route that includes asymmetric palladium-catalyzed α-arylation of a ketone with an aryl bromide that was generated by sterically controlled halogenation via iridium-catalyzed C-H borylation. This asymmetric α-arylation creates the benzylic quaternary stereogenic center present in the taiwaniaquinoids. The synthesis was completed efficiently by developing a Lewis acid-promoted cascade to construct the [6,5,6] tricyclic core of an intermediate common to the synthesis of a number of taiwaniaquinoids. Through the preparation of these compounds, we demonstrate the utility of constructing benzylic quaternary stereogenic centers, even those lacking a carbonyl group in the α-position, by asymmetric α-arylation.
Department of Chemistry, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801-3602, United States.
Xuebin
X
Liao
Levi M
LM
Stanley
John F
JF
Hartwig
D001896:Boron Compounds / Q000737:chemistry*; D002384:Catalysis; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
D001896:Boron Compounds; D004224:Diterpenes; C505702:taiwaniaquinol B; C516088:taiwaniaquinone H; D007495:Iridium; D010165:Palladium
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