403805-96-9Relevant academic research and scientific papers
Dramatic rate enhancement with preservation of stereospecificity in the first metal-catalyzed additions of allylboronates
Kennedy, Jason W. J.,Hall, Dennis G.
, p. 11586 - 11587 (2002)
This communication successfully challenges the perception that the additions of allylbonates to aldehydes cannot be catalyzed effectively by added Lewis acids. Using a novel class of isomerically pure, tetrasubstituted 2-alkoxycarbonyl allylboronates (1),
Lewis acid catalyzed allylboration: Discovery, optimization, and application to the formation of stereogenic quaternary carbon centers
Kennedy, Jason W. J.,Hall, Dennis G.
, p. 4412 - 4428 (2007/10/03)
A full account of the development of the first catalytic manifold for the additions of allylboronates to aldehydes is described. The thermal additions (both diastereospecific and enantioselective) of 2-carboxyester 3,3-disubstituted allylboronates 1 to both aromatic and aliphatic aldehydes give biologically and synthetically important exo-methylene butyrolactones 2 containing a β-quaternary carbon center. Although the thermal reaction requires 14 d at room temperature to reach completion, the presence of certain metal salts allows for a 12-16 h reaction while preserving the dia-stereospecificity observed in the uncatalyzed process. Preliminary mechanistic studies on the origin of the catalytic effect are described as well as stereoselective transformations of lactones 2 into cyclic and acyclic stereotriads with potential usefulness as synthetic intermediates.
Novel isomerically pure tetrasubstituted allylboronates: Stereocontrolled synthesis of α-exomethylene γ-lactones as aldol-like adducts with a stereogenic quaternary carbon center
Kennedy, Jason W. J.,Hall, Dennis G.
, p. 898 - 899 (2007/10/03)
In spite of their inherent isomerization tendency and low reactivity, 1-alkoxycarbonyl vinylcopper(I) intermediates from the conjugate addition of organocuprates onto acetylenic esters were trapped with very high cis-addition selectivity with iodomethylboronic esters in the presence of HMPA. The resulting isomerically pure 3,3-disubstituted allylboronates react with aldehydes in a highly diastereo- and enantioselective manner, providing α-exomethylene γ-lactones with a stereogenic quaternary β-carbon center. Copyright
