Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
作者:Lujia Mao、Rüdiger Bertermann、Katharina Emmert、Kálmán J. Szabó、Todd B. Marder
DOI:10.1021/acs.orglett.7b03294
日期:2017.12.15
An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as
On the viability of 5-endo-dig cyclisations of O-propargylic hydroxylamine derivatives, leading to 2,5-dihydroisoxazoles (3-isoxazolines)
作者:Oliver F. Foot、David W. Knight、Ai Cheng Lilian Low、YingFa Li
DOI:10.1016/j.tetlet.2006.11.114
日期:2007.1
O-Propargylic hydroxylamines undergo smooth 5-endo-dig cyclisations upon exposure to 3 equiv of molecular iodine to give respectable yields of the corresponding 4-iodo-2,5-dihydroisoxazoles, which should find a number of applications as intermediates for syntheses amongst this useful class of heterocycles.
A Highly Efficient Preparative Method of α-Ylidene-β-Diketones via Au<sup>III</sup>-Catalyzed Acyl Migration of Propargylic Esters
作者:Shaozhong Wang、Liming Zhang
DOI:10.1021/ja062777j
日期:2006.7.1
A highlyefficient synthesis of α-alkylidene or benzylidene-β-diketones from readily available propargylic esters has been developed. The proposed key transformation is a novel intramolecular acyl migration to nucleophilic AuIII−C(sp2) bonds. Noteworthy features of this method are its efficiency and stereoselectivity. The yields of this reaction were mostly close to quantitative, and high to excellent
Stereoconvergent ‘one-pot’ tandem [2,3]-Wittig-anionic oxy-Cope rearrangement of acyclic bis-allylic ethers in the diastereoselective synthesis of substituted tetrahydropyrans
作者:Nicholas Greeves、Katya Jane Vines
DOI:10.1039/c39940001469
日期:——
The unsaturated alcohols derived from a âone-potâ tandem [2,3]-Wittig-anionic oxy-Cope (AOC) rearrangement undergo a halocyclisation reaction with iodine in acetonitrile to give substituted tetrahydropyrans with a high degree of stereocontrol.
Lewis Base-Catalyzed Additions of Alkynes Using Trialkoxysilylalkynes
作者:Robert B. Lettan、Karl A. Scheidt
DOI:10.1021/ol051030f
日期:2005.7.1
[reaction: see text]. The Lewis base-catalyzedadditions of alkynyl nucleophiles to aldehydes, ketones, and imines is described. Mechanistic studies strongly indicate that the use of new triethoxysilylalkynes facilitates access of a reactive hypervalent silicate intermediate. This activated carbon nucleophile subsequently undergoes rapid addition to carbonyl compounds and imines, thus affording the