119441-92-8Relevant academic research and scientific papers
Computational and Experimental Study on Selective sp2/sp3 or Vinylic/Aryl Carbon-Hydrogen Bond Activation by Platinum(II): Geometries and Relative Stability of Isomeric Cycloplatinated Compounds
Li, Yumin,Carroll, Jeffrey,Simpkins, Bradley,Ravindranathan, Deepak,Boyd, Christopher M.,Huo, Shouquan
, p. 3303 - 3313 (2015)
Cyclometalating ligands 6-(1-phenylethyl)-2,2′-bipyridine (L4), 6-(1-phenylvinyl)-2,2′-bipyridine (L5), and 6-(prop-1-en-2-yl)-2,2′-bipyridine (L6) were synthesized by the Negishi coupling of 6-bromo-2,2′-bipyridine with the corresponding organozinc reagents. The reaction of L4 with K2PtCl4 produced only the cycloplatinated compound 4a via sp2 C-H bond activation. The reactions of L5 and L6 produced exclusively the cycloplatinated compounds 5b and 6a, respectively, via vinylic C-H bond activation. DFT calculations were performed on 12 possible cycloplatination products from the reaction of N-alkyl-N-phenyl-2,2′-bipyridin-6-amine (alkyl = methyl (L1), ethyl (L2), and isopropyl (L3)) and L4-L6. The results show that compounds 1b-3b resulting from the sp3 C-H bond activation of L1-L3 are thermodynamic products, and their relative stability is attributed to the planar geometry that allows for a better conjugation. Similar reasoning also applies to the stability of products from vinylic C-H bond activation of L5 and L6. The relative stability of isomeric cycloplatinated compounds 4a and 4b may be due to the different strengths of C-Pt bonds. The steric interaction is the major cause of severe distortion from a planar coordination geometry in the cycloplatinated compounds, which leads to instability of the corresponding cyclometalated products and a higher kinetic barrier for C-H bond activation.
Synthesis of (+)-discodermolide by catalytic stereoselective borylation reactions
Yu, Zhiyong,Ely, Robert J.,Morken, James P.
supporting information, p. 9632 - 9636 (2014/10/15)
The marine natural product (+)-discodermolide was first isolated in 1990 and, to this day, remains a compelling synthesis target. Not only does the compound possess fascinating biological activity, but it also presents an opportunity to test current methods for chemical synthesis and provides an inspiration for new reaction development. A new synthesis of discodermolide employs a previously undisclosed stereoselective catalytic diene hydroboration and also establishes a strategy for the alkylation of chiral enolates. Furthermore, this synthesis of discodermolide provides the first examples of the asymmetric 1,4-diboration of dienes and borylative diene-aldehyde couplings in complex-molecule synthesis. Borylation-based synthesis: The development of a strategy for stereocontrol in catalytic diene hydroboration enables the synthesis of a critical building block for the assembly of (+)-discodermolide. Combined with asymmetric catalytic diboration, hydroformylation, and borylative aldehyde-diene coupling reactions, (+)-discodermolide could then be prepared from simple hydrocarbon-based building blocks.
