Enantioselective reductive coupling of alkynes and alpha-keto aldehydes via rhodium-catalyzed hydrogenation: an approach to bryostatin substructures.
Hydrogen-mediated reductive coupling of glyoxal 2 and 1,3-enyne 3 provides alpha-hydroxy ketone 4 in 70% yield and 91% enantiomeric excess. Notably, the benzylic ether and diene side chain of 4 remain intact under the conditions of hydrogen-mediated coupling. In four steps, alpha-hydroxy ketone 4 is converted to pyrans 8 and 9, which embody key structural features of the bryostatin recognition domain.
Cho
Chang-Woo
CW
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Krische
Michael J
MJ
D000447:Aldehydes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D054713:Bryostatins; D002384:Catalysis; D006865:Hydrogenation; D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011714:Pyrans / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D000480:Alkynes; D054713:Bryostatins; D018942:Macrolides; D011714:Pyrans; C046785:bryostatin 1; D012238:Rhodium