Improved Dienophilicity of Nitrocycloalkenes: Prospects for the Development of a <i>trans</i>-Diels−Alder Paradigm
作者:Woo Han Kim、Jun Hee Lee、Samuel J. Danishefsky
DOI:10.1021/ja9058926
日期:2009.9.9
The development of an efficient and stereoselective trans-Diels-Alder paradigm is described. A central element of this transformation is the introduction of a temporary dienophilic functionality (A), which serves both to activate the substrate for Diels-Alder cycloaddtion and, through its subsequent removal, to facilitate conversion of the cis-fused cycloadducts to the trans-fused series.
Assistance d'un groupe voisin pour des tosylates secondaires β substitues diequatoriaux dans l'hexafluoroisopropanol 97%
作者:J. Laureillard、E. Casadevall
DOI:10.1016/s0040-4020(01)88454-4
日期:1984.1
Solvolysis rates in methanol and 97% hexafluoroisopropanol (HFIP) for four β-methyl and β-phenyl bicyclic tosylates, show that solventnucleophilicassistance is operating in the former solvent. However, in 97% HFIP, for three of the mentioned compounds, the mechanism involves π or σ neighboring group assistance. The factors influencing the occurrence of these processes are discussed. Owing to these
β-甲基和β-苯基四环甲苯磺酸盐在甲醇和97%六氟异丙醇(HFIP)中的溶剂分解速率表明,溶剂亲核助剂正在前一种溶剂中运行。但是,在97%的HFIP中,对于上述三个化合物,该机理涉及π或σ邻基团辅助。讨论了影响这些过程发生的因素。由于在用于获得k c参考机理的非亲核溶剂中存在这些可能的邻近基团辅助作用,因此得出结论,必须谨慎使用提议作为溶剂亲核助剂的定量评估方法的k a / k c比值。
Thermal valence isomerization of cis-fused bicyclic cyclobutenes. A study of orbital symmetry control
作者:William G. Dauben、Drake M. Michno
DOI:10.1021/ja00399a025
日期:1981.5
Syntheses of isomerically pure reference octalins and hydrindanes
作者:Jun Hee Lee、Woo Han Kim、Samuel J. Danishefsky
DOI:10.1016/j.tetlet.2009.07.068
日期:2009.9
We describe herein the development of efficient and stereoselective synthetic routes to a range of cis- and trans-octalin and hydrindane target compounds. (C) 2009 Elsevier Ltd. All rights reserved.
13C NMR spectroscopy of [4.n.0] bicyclic compounds: Assignment of the ring junction configuration from ring junction configuration from ring junction13C chemical shifts—application and limits