Hydroxylamine catalyzed Nazarov cyclizations of divinyl ketones
摘要:
The first examples of iminium catalyzed Nazarov cyclizations of divinyl ketones are presented. Experiments describing hydroxylamine catalysis of the cyclization of eight alpha-alkoxy divinyl ketones (60-79% yield) and one unactivated divinyl ketone (38% yield) are reported. Phenyl substitution at the beta-position of the divinyl ketone inhibits cyclization, whereas beta-alkyl substituted beta-alkoxy divinyl ketones readily cyclize. (C) 2015 Elsevier Ltd. All rights reserved.
Nazarov Cyclization of Divinyl and Arylvinyl Epoxides: Application in the Synthesis of Resveratrol-Based Natural Products
作者:Gangarajula Sudhakar、Kovela Satish
DOI:10.1002/chem.201500362
日期:2015.4.20
New variation in the Nazarovcyclization has been developed by preparing divinyl and arylvinyl epoxides as pentadienyl cation precursors for the first time. Highly substituted cyclopentadienes, hydrindienes, and indenes were synthesized to demonstrate the compatibility of this reaction with substrates bearing a variety of substitutions and having different types of epoxides. Application of this method
Domino Electrocyclization/Azide-Capture/Schmidt Rearrangement of Dienones: One-Step Synthesis of Dihydropyridones from Simple Building Blocks
作者:Dong Song、Ali Rostami、F. G. West
DOI:10.1021/ja071041z
日期:2007.10.1
proceed via nucleophilic trapping of the 2-oxidocyclopentenyl intermediate, followed by Schmidt-type rearrangement to give a transient 1,4-dipole. In unsymmetrical examples, complete regioselectivity in favor of attack on the less substituted side was observed. The 1,4-dipole intermediate then rearranges to the observed dihydropyridone, via either proton transfer or 1,5-hydride shift.
Olefination of α,α′-Divinyl Ketones through Catalytic Meyer−Schuster Rearrangement
作者:Curtis J. Rieder、Karl J. Winberg、F. G. West
DOI:10.1021/jo101497f
日期:2011.1.7
followed by catalytic Meyer−Schuster rearrangement has been developed for the olefination of 1,4-pentadien-3-ones to afford [3]dendralenes. Many of the traditional methods for the Meyer−Schuster rearrangement of alkynyl carbinols are not suitable with these highly unsaturated substrates because of their acid sensitivity. Unexpected reactivity during attempted rearrangement, including Nazarov-type electrocyclizations
Negishi cross-coupling reactions are described. This method readily provides various enones from enol triflates and diorganozinc reagents with catalytic amounts of nickel(II) chloride–4,4′-dimethoxyl-2,2′-bipyridyl under carbonmonoxide atmosphere. The rate of carbonmonoxide insertion is increased by the addition of lithium or magnesium halides and the use of polar solvents. Alkenyl iodides can also
Convenient route to centro-substituted triquinacene skeletons via the interrupted Nazarov reaction
作者:Ashantai Yungai、F.G. West
DOI:10.1016/j.tetlet.2004.05.072
日期:2004.7
cation with 2,3-dimethyl-1,3-butadiene are cleaved by ozonolysis to furnish triketones. In the presence of methanolic KOH, these triones undergo tandem aldol additions to furnish centro-hydroxylated triquinacene skeletons.