Regioselective synthesis of highly substituted enol esters from ketoketene dimer β-lactones
作者:Eric C Salo、Kyle R Dayak、Jacob Huxford、Pei-Hsun Wei、Nicholas J Peraino、Nessan Joseph Kerrigan
DOI:10.3998/ark.5550190.p008.443
日期:——
A method for the regioselectivesynthesis of highlysubstitutedenolestersfromketoketenedimersβ-lactones is described. Methylphenylketene dimer was subjected to a sequential one-pot reaction sequence involving ring-opening with an organolithium to give an enolate intermediate, followed by enolate acylation with an acyl chloride to give a highlysubstitutedenolester as the final product. Complete
Asymmetric Dimerization of Disubstituted Ketenes Catalyzed by N-Heterocyclic Carbenes
作者:Hui Lv、Yan-Rong Zhang、Xue-Liang Huang、Song Ye
DOI:10.1002/adsc.200800532
日期:——
A series of chiral N-heterocycliccarbenes (NHCs), derived from L-pyrogutamic acid, were found to be efficient catalysts for the asymmetricdimerization of alkylarylketenes to give the corresponding α-quaternary β-alkylidenyl-β-lactones in good yields with up to 97% ee. A chiral NHC with a proximal hydroxy group is superior in comparison with the corresponding NHC with its hydroxy group protected.
Phosphine-Catalyzed Asymmetric Synthesis of β-Lactones from Arylketoketenes and Aromatic Aldehydes
作者:Mukulesh Mondal、Ahmad A. Ibrahim、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1021/ol100075m
日期:2010.4.16
In this paper, the development of a chiral phosphine-catalyzed formal [2 + 2] cycloaddition of aldehydes and ketoketenes that provides access to a variety of highly substituted beta-lactones (14 examples) is reported. The BINAPHANE catalytic system displays excellent enantioselectivity (seven examples with ee >= 90%) and high diastereoselectivity favoring formation of the trans-diastereomer (nine examples with dr >= 90:10).
Phosphine-catalyzed stereoselective dimerizations of ketenes
作者:Ahmad A. Ibrahim、Pei-Hsun Wei、Gero D. Harzmann、Divya Nalla、Mukulesh Mondal、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1016/j.tet.2020.131838
日期:2021.1
Full details of optimisation studies of the phosphine-catalyzed ketene homodimerization reaction and the detailed development of an asymmetric variant are discussed. Studies towards the development of a phosphine-catalyzed ketene heterodimerization reaction are revealed. A discussion of possible reaction mechanisms for the dimerization reactions, supported by spectroscopic analysis of intermediates
Josiphos-Catalyzed Asymmetric Homodimerization of Ketoketenes
作者:Ahmad A. Ibrahim、Pei-Hsun Wei、Gero D. Harzmann、Nessan J. Kerrigan
DOI:10.1021/jo101867m
日期:2010.11.19
phosphine-catalyzed homodimerization of ketoketenes that provides access to a variety of highlysubstitutedketoketenedimerβ-lactones (11 examples) is reported. The Josiphos catalytic system displays good to excellent enantioselectivity (up to 96% ee). Ring-opening reactions of the enantioenriched ketoketenedimers were also carried out to access 1,3-diketones, enolesters, and β-hydroxyketones with good