Intramolecular Anodic Olefin Coupling Reactions: The Use of a Nitrogen Trapping Group
作者:Hai-Chao Xu、Kevin D. Moeller
DOI:10.1021/ja806259z
日期:2008.10.15
Anodicolefincouplingreactionsusing a tosylamine trapping group have been studied. The cyclizations are favored by the use of a less-polar radical cation and more basic reaction conditions. The most significant factor for obtaining good yields of cyclic product is the use of the more basic reaction conditions. The cyclizations allow for the rapid synthesis of substituted proline derivatives.
Construction of dihydropyran-bridged macrocycles by inverse-electron-demand Diels–Alder reaction
作者:Xiaomei Dong、Qingxia Wang、Qian Zhang、Shuai Xu、Zhihong Wang
DOI:10.1016/j.tet.2013.10.101
日期:2013.12
A variety of dihydropyran-bridged macrocyclic structures were constructed by the inverse-electron-demand Diels Alder reaction of 2-oxo-4-aryl-but-3-enoates. Controlling of the tether length and the position of the activating substituent in the substrates would guide the reaction to the formation of four different types of polycyclic frames, namely bicyclic [n.3.1], bicyclic [n.2.2], tricyclic [n.3.1.1], and tricyclic [n.2.2.2] macrocycles. The intermolecular/intramolecular selectivity of the Diels Alder reaction was virtually governed by the tether length. The reactions were carried out rapidly under mild conditions, and offered a practical method for creating bridged polycyclic structures with large rings from acyclic precursors. (C) 2013 Elsevier Ltd. All rights reserved.
A Versatile Cascade of Intramolecular Vilsmeier−Haack and Azomethine Ylide 1,3-Dipolar Cycloaddition toward Tricyclic Cores of Alkaloids
作者:François Lévesque、Guillaume Bélanger
DOI:10.1021/ol802010n
日期:2008.11.6
In the pursuit of synthetic efficiency, we developed an innovative one-pot transformation of linear substrates into bi- and tricyclic adducts using a cascade of amide activation, nucleophilic cyclization, azomethine ylide generation, and subsequent inter- or intramolecular 1,3-dipolar cycloaddition. Despite the high density and variety of functional groups on the substrates, the sequence occurred with perfect chemoselectivity with good to excellent yields.