96481-55-9Relevant articles and documents
Ambruticins: tetrahydropyran ring formation and total synthesis
Bowen, James I.,Crump, Matthew P.,Wang, Luoyi,Willis, Christine L.
supporting information, p. 6210 - 6215 (2021/07/28)
The ambruticins are a family of polyketide natural products which exhibit potent antifungal activity. Gene knockout experiments are in accord with the proposal that the tetrahydropyran ring of the ambruticins is formedviathe AmbJ catalysed epoxidation of the unsaturated 3,5-dihydroxy acid, ambruticin J, followed by regioselective cyclisation to ambruticin F. Herein, a convergent approach to the total synthesis of ambruticin J is described as well as model studies involving epoxidation and cyclisations of unsaturated hydroxy esters to give tetrahydropyrans and tetrahydrofurans. The total synthesis involves preparation of three key fragments which were unitedviaa Suzuki-Miyaura cross-coupling and Julia-Kocienski olefination to generate the required carbon framework. Global deprotection to a triol and selective oxidation of the primary alcohol gave, after hydrolysis of the lactone, ambruticin J.
Mechanistic Insight into Palladium-Catalyzed Cycloisomerization: A Combined Experimental and Theoretical Study
Mekareeya, Aroonroj,Walker, P. Ross,Couce-Rios, Almudena,Campbell, Craig D.,Steven, Alan,Paton, Robert S.,Anderson, Edward A.
supporting information, p. 10104 - 10114 (2017/08/03)
The cycloisomerization of enynes catalyzed by Pd(OAc)2 and bis-benzylidene ethylenediamine (bbeda) is a landmark methodology in transition-metal-catalyzed cycloisomerization. However, the mechanistic pathway by which this reaction proceeds has remained unclear for several decades. Here we describe mechanistic investigations into this reaction using enynamides, which deliver azacycles with high regio- and stereocontrol. Extensive 1H NMR spectroscopic studies and isotope effects support a palladium(II) hydride-mediated pathway and reveal crucial roles of bbeda, water, and the precise nature of the Pd(OAc)2 pre-catalyst. Computational studies support these mechanistic findings and lead to a clear picture of the origins of the high stereocontrol that can be achieved in this transformation, as well as suggesting a novel mechanism by which hydrometalation proceeds.
Asymmetric syntheses of 8-oxabicyclo[3,2,1]octanes: A cationic cascade cyclization
Li, Bin,Zhao, Yu-Jun,Lai, Yin-Chang,Loh, Teck-Peng
supporting information; experimental part, p. 8041 - 8045 (2012/09/05)
High octane: A novel and practical syntheses of 8-oxabicyclo[3.2.1]octanes using a cationic cascade cyclization reaction has been developed (see scheme; TIPS=triisopropylsilyl). The diastereomer of the cyclization product isolated depends upon whether the acetal or aldehyde substrate is used. Copyright
