Ruthenium(0) Catalyzed Endiyne−α-Ketol [4 + 2] Cycloaddition: Convergent Assembly of Type II Polyketide Substructures via C–C Bond Forming Transfer Hydrogenation
摘要:
Upon exposure of 3,4-benzannulated 1,5-diynes (benzo-endiynes) to alpha-ketols (alpha-hydroxyketones) in the presence of Ru(0) catalysts derived from Ru-3(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 alpha-ketol mediated transfer hydrogenolysis. This process provides a new, convergent means of assembling Type II polyketide substructures.
Photochemical Rearrangement of Enediynes: Is a “Photo-Bergman” Cyclization a Possibility?
作者:Ariella Evenzahav、Nicholas J. Turro
DOI:10.1021/ja9722943
日期:1998.3.1
when the double bond of the enediyne was of aromatic character. Triplet sensitization studies and laser flash photolysis experiments point toward radical mechanisms taking place during formation of both classes of products, with the photoreduction products forming from the excited triplet state and the cyclized naphthyl products forming from either the singlet or the triplet states. For the cyclization
The synthesis of trans-(Me3CO)3WCCHCHCW(OCMe3)3, cis,cis-(Me3CO)3WCCHCHCCCHCHCW(OCMe3)3, and related metal-capped ene-ynes, and evaluation of them as catalysts for preparing polydiacetylenes
作者:Steven A. Krouse、Richard R. Schrock
DOI:10.1016/0022-328x(88)89027-2
日期:1988.11
Ruthenium(0) Catalyzed Endiyne−α-Ketol [4 + 2] Cycloaddition: Convergent Assembly of Type II Polyketide Substructures via C–C Bond Forming Transfer Hydrogenation
作者:Aakarsh Saxena、Felix Perez、Michael J. Krische
DOI:10.1021/jacs.5b02755
日期:2015.5.13
Upon exposure of 3,4-benzannulated 1,5-diynes (benzo-endiynes) to alpha-ketols (alpha-hydroxyketones) in the presence of Ru(0) catalysts derived from Ru-3(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 alpha-ketol mediated transfer hydrogenolysis. This process provides a new, convergent means of assembling Type II polyketide substructures.
Photochemical analogue of the bergman cycloaromatization reaction
作者:Nicholas J. Turro、Ariella Evenzahav、K.C. Nicolaou
DOI:10.1016/0040-4039(94)88250-9
日期:1994.10
Irradiation of an enediyne analog yields a cyclized product expected from a thermal Bergman rearrangement.