Facile allylboration of ketones with β-benzyloxy-γ,γ-difluoroallylboronate: Preparation of gem-difluorinated homoallylic tert-alcohols
摘要:
The reaction of beta-benzyloxy-gamma,gamma-difluoroallylboronate, at room temperature and in the absence of catalysts, with a variety of aromatic and aliphatic ketones of varying sterics and electronic requirements furnishes fluorinated homoallylic tert-alcohols in 62-82% yields. Representatives of these alcohols were converted to their corresponding alpha,alpha-difluoro-beta-hydroxy ketones in 73-85% yields. (C) 2008 Elsevier B.V. All rights reserved.
Novel Isomerically Pure Tetrasubstituted Allylboronates: Stereocontrolled Synthesis of α-Exomethylene γ-Lactones as Aldol-Like Adducts with a Stereogenic Quaternary Carbon Center
作者:Jason W. J. Kennedy、Dennis G. Hall
DOI:10.1021/ja016391e
日期:2002.2.1
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
Lewis Acid Catalyzed Allylboration: Discovery, Optimization, and Application to the Formation of Stereogenic Quaternary Carbon Centers
作者:Jason W. J. Kennedy、Dennis G. Hall
DOI:10.1021/jo049773m
日期:2004.6.1
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
Highly Diastereoselective Synthesis of Methylenecyclobutanes by Merging Boron‐Homologation and Boron‐Allylation Strategies
作者:Michael Eisold、Dorian Didier
DOI:10.1002/anie.201507444
日期:2015.12.21
A highlydiastereoselectivesynthesis of methylenecyclobutanes possessing a quaternary stereocenter is reported, in which boronhomologation of an easily‐generated cyclobutenylmetal species is performed, followed by an allylation reaction. Combining three steps in a one‐pot process further optimized the method, which afforded the expected adducts in excellent yields and stereoselectivity, starting
provides a series of chiral γ,γ-difluoroallylboronates. Asymmetric fluoroallylboration of aldehydes with a 2-phenylbornane-2,3-diol-derived reagent provides gem-difluorinated homoallylalcohols in good yields and 77–95% ee. Preparation of a chiral α-pyrone in >99% ee has also been described.
Synthesis of (+)-Bullatacin via the Highly Diastereoselective [3+2] Annulation Reaction of a Racemic Aldehyde and a Nonracemic Allylsilane
作者:Jennifer M. Tinsley、Eric Mertz、Pek Y. Chong、Robert-André F. Rarig、William R. Roush
DOI:10.1021/ol051719k
日期:2005.9.1
[reaction: see text] A total synthesis of (+)-bullatacin has been accomplished via a diastereoselective [3+2] annulation reaction of the highly enantiomerically enriched allylsilane 3 and racemic aldehyde 4, which provides the key bis-tetrahydrofuran fragment 15 with > or = 20:1 ds.