25129-61-7Relevant articles and documents
A New Approach to Models of the 4,5-Dihydroxycyclopentenone Core of the Kodaistatins A–D: Elucidation of the Diol Configuration in Kodaistatin A
Peter, David,Brückner, Reinhard
, p. 12104 - 12109 (2017)
The kodaistatins A–D are strongly anti-diabetic natural products from Aspergillus terreus that hold some promise of a novel diabetes cure. However, considerations of that kind face two drawbacks: 1) The kodaistatins A–D contain a heavily substituted pulvinone/cyclopentenone combination; 2) they are 1,2-diols, the 3D structures of which have not been assigned yet. However, we can exclude two of the four possible stereostructures. We conclude that kodaistatin A is a trans-, not a cis-diol from NMR comparisons with a pair of cis, trans-isomeric kodaistatin models, which we synthesized in 11 and 12 steps, respectively. The stereocenters of the diol moiety arose from stereocomplementary, highly diastereoselective aldol additions of a lithium enolate or the corresponding silyl ketene acetal. The cyclopentenone moieties stemmed from intramolecular aldol additions and ensuing dehydrations. The requisite enolates were obtained by the reduction of α-bromoketones with samarium diiodide.
A New Platinum Complex Catalyzed Reaction Involving Nucleophilic Substitution at the Central Carbon Atom of the π-Allyl Ligand
Kadota, Joji,Komori, Shinji,Fukumoto, Yoshiya,Murai, Shinji
, p. 7523 - 7527 (2007/10/03)
The reaction of 2-chloro-allyl acetate with sodium ethyl acetoacetate in the presence of a platinum-(0) complex gave furan derivatives. The key feature of this new platinum-catalyzed reaction is the nucleophilic substitution at the central carbon atom of π-allyl complexes. The regioselectivity of the nucleophilic attacks (central or terminal) is dependent on the pKa of the nucleophile. In addition, a labeling experiment revealed that a rapid syn-anti isomerization of the (π-allyl) platinum complexes occurs.
