Two tandem sequential reactions catalyzed by [Au], N-heterocyclic carbenes (NHC) and organic bases
摘要:
Herein we describe two coupling reactions of aldehydes and activated alkynes to give chalcones or alkenyl esters depending on the base used. Chalcones were obtained by activation of alkynes by Au-I and of aldehydes by NHC in presence of triethylamine. Alkenyl esters were obtained via generation of gold nanoparticles, aerial oxidation of aldehydes to carboxylates and their subsequent nucleophilic addition to the alkyne functionality. (C) 2011 Elsevier Ltd. All rights reserved.
Ring-opening of 3-substituted 4-isoxazolines, proceeding through the intermediate isoxazolinium salts, follows two competing reaction pathways leading to alpha,beta-enones and enamines respectively. The rearrangement courses can be controlled as a function of substitution pattern and experimental conditions.
Cerium-Catalyzed Formal Cycloaddition of Cycloalkanols with Alkenes through Dual Photoexcitation
We describe a synergistic utilization of cerium photocatalysis and photoinduced electron transfer catalysis that enables an atom- and step-economical ring expansion of readily available cycloalkanols. This operationally simple protocol provides rapid access to privileged and synthetically challenging bridged lactones. The mild catalytic manifold has been adapted to continuous flow for scale-up applications and employed for the concise synthesis of polycyclic core of nepalactones.
Additionen von Aldehyden an aktivierte Doppelbindungen; XXXI<sup>1</sup>. Synthesen und Reaktionen von verzweigten Tetracarbonyl-Verbindungen
作者:Hermann Stetter、Friedrich Jonas
DOI:10.1055/s-1981-29549
日期:——
Preparation of Tetrasubstituted Furans via Intramolecular Wittig Reactions with Phosphorus Ylides as Intermediates
作者:Tzu-Ting Kao、Siang-en Syu、Yi-Wun Jhang、Wenwei Lin
DOI:10.1021/ol101080q
日期:2010.7.2
functional furans can be efficiently generated in one step at room temperature within 10 min to 21 h in moderate to high yields (60−99%). The reaction was proposed to proceed via intramolecular Wittig-type reactions, using phosphorus ylides as intermediates.
Two tandem sequential reactions catalyzed by [Au], N-heterocyclic carbenes (NHC) and organic bases
作者:Mauro F.A. Adamo、Gea Bellini、Surisetti Suresh
DOI:10.1016/j.tet.2011.05.135
日期:2011.8
Herein we describe two coupling reactions of aldehydes and activated alkynes to give chalcones or alkenyl esters depending on the base used. Chalcones were obtained by activation of alkynes by Au-I and of aldehydes by NHC in presence of triethylamine. Alkenyl esters were obtained via generation of gold nanoparticles, aerial oxidation of aldehydes to carboxylates and their subsequent nucleophilic addition to the alkyne functionality. (C) 2011 Elsevier Ltd. All rights reserved.