Ruthenium(0) Catalyzed Endiyne-α-Ketol [4 + 2] Cycloaddition: Convergent Assembly of Type II Polyketide Substructures via C-C Bond Forming Transfer Hydrogenation.
Upon exposure of 3,4-benzannulated 1,5-diynes (benzo-endiynes) to α-ketols (α-hydroxyketones) in the presence of Ru(0) catalysts derived from Ru3(CO)12 and RuPhos or CyJohnPhos, successive redox-triggered C-C coupling occurs to generate products of [4 + 2] cycloaddition. The proposed catalytic mechanism involves consecutive alkyne-carbonyl oxidative couplings to form transient oxaruthanacycles that suffer α-ketol mediated transfer hydrogenolysis. This process provides a new, convergent means of assembling Type II polyketide substructures.
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, United States.
Aakarsh
A
Saxena
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, United States.
Felix
F
Perez
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, United States.
Michael J
MJ
Krische
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006865:Hydrogenation; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D061065:Polyketides / Q000138:chemical synthesis* / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*
D000480:Alkynes; D007659:Ketones; D009942:Organometallic Compounds; D061065:Polyketides; D012428:Ruthenium