N-Heterocyclic Carbene Catalyzed Ring Expansion of Formylcyclopropanes: Synthesis of 3,4-Dihydro-α-pyrone Derivatives
摘要:
N-Heterocyclic carbene catalyzed ring expansion of readily accessible 2-acyl-l-formylcyclopropanes was developed. With 5 mol % of triazoliurn salt 5 and 30 mol % of DBU, ring expansion of various 2-acyl-l-formylcyclopropanes led to 3,4-dihydro-alpha-pyrones in good to excellent yields.
Facile Synthesis of 3,4-Dihydro<i>-</i>α-pyrones via Michael Reaction-O-Acylation Sequences
作者:Shû Kobayashi、Mitsuhiro Moriwaki
DOI:10.1055/s-1997-3229
日期:1997.5
3,4-Dihydro-α-pyrones were prepared in excellent yields with high stereoselectivities by the trityl salt-catalyzed Michael reaction and sequential intramolecular O-acylation of the intermediary silyl enol ethers using a mercury (II) salt (one-pot reaction).
A new approach to 4,6-disubstituted-3,4-dihydropyran-2-ones by Domino Michael addition-cyclization reaction under PTC conditions
作者:Nicoletta Gaggero、Domenico C.M. Albanese、Donatella Nava
DOI:10.1016/j.tet.2014.09.022
日期:2014.11
Domino Michael addition-cyclization reactions of α,β-unsaturatedcarbonylcompounds with activated 1,3-dithiane-2-carbothioate esters under solid-liquid phase transfer catalysis conditions provide 4,6-disubstituted-3,4-dihydropyran-2-one-3,3-dithioacetals in good chemical yield. Desulfurization proceeds chemoselectively under mild conditions affording 3,4-dihydropyran-2-ones in high yields.
<i>N</i>-Heterocyclic Carbene-Catalyzed Generation of α,β-Unsaturated Acyl Imidazoliums: Synthesis of Dihydropyranones by their Reaction with Enolates
作者:Sarah J. Ryan、Lisa Candish、David W. Lupton
DOI:10.1021/ja905501z
日期:2009.10.14
Catalytic generation of alpha,beta-unsaturated acyl imidazolium cations and enolates has been achieved, and their involvement in a Michael addition acylation sequence exploited, to provide a range of dihydropyranones. alpha,beta-Unsaturated enol esters, or alpha,beta-unsaturated acid fluorides in association with TMS enol ethers, serve as appropriate substrates for this reaction. The transformation
Vorlaender; Knoetzsch, Justus Liebigs Annalen der Chemie, 1897, vol. 294, p. 332
作者:Vorlaender、Knoetzsch
DOI:——
日期:——
Asymmetric Access to the Smallest Enolate Intermediate via Organocatalytic Activation of Acetic Ester
作者:Shaojin Chen、Lin Hao、Yuexia Zhang、Bhoopendra Tiwari、Yonggui Robin Chi
DOI:10.1021/ol402877n
日期:2013.11.15
An NHC-catalyzed activation of acetic esters to afford enolate intermediates is disclosed. The catalytically generated triazolium enolate intermediates serve as two-carbon nucleophiles that undergo highly enantioselective reactions with enones and alpha,beta-unsaturated imines to give a-unsubstituted delta-lactones and lactams, respectively.