Aerobic copper-catalyzed oxidative [6C+1C] annulation: an efficient route to seven-membered carbocycles
作者:Xiao Liu、Lingjuan Zhang、Xianxiu Xu、Shan Wang、Ling Pan、Qian Zhang、Qun Liu
DOI:10.1039/c4cc03095h
日期:——
It has been revealed for the first time that co-promoted by CuCl and NaH in the presence of molecularoxygen (air), the reaction of dicinnamoyl ketene dithioacetals as the acyclic C6 synthons with ethyl cyanoacetate gives functionalized seven-membered carbocycles. A mechanism is proposed involving a tandem Michael addition-intramolecular radical cyclization-benzyl C(sp(3))-H bond oxidation.
Facile [7C+1C] Annulation as an Efficient Route to Tricyclic Indolizidine Alkaloids
作者:Xianxiu Xu、Lingjuan Zhang、Xiqing Liu、Ling Pan、Qun Liu
DOI:10.1002/anie.201303604
日期:2013.8.26
A handle on annulation: The two alkenoyl moieties of the cyclic dithiolane are parallel to each other and enables the [7C+1C] annulation with ethyl isocyanoacetate to occur. As a result, tricyclicindolizidinealkaloids are constructed by a two‐step, base‐catalyzed [7C+1C] annulation/intramolecular cyclization with subsequent reduction/cyclization.
Bicyclization of Isocyanides: A Synthetic Strategy for Fused Pyrroles
作者:Lingjuan Zhang、Xianxiu Xu、Wenming Xia、Qun Liu
DOI:10.1002/adsc.201100501
日期:2011.10
On the isocyanide carbon atom, two CC sigma bonds are formed in the bicyclization reaction of the readily available acyclic substrates with tosylmethyl isocyanides. The reaction can proceed under extremely mild and metal-free conditions to give the products in high to excellent yields. The powerful potential of this strategy deserves attention because it is a new paradigm for trapping of the incipient