NH-Isoxazolo-bicycles; new molecular scaffolds for organocatalysis
摘要:
A new scaffold for organocatalysis of the Diels-Alder reaction is disclosed; an isoxazolidine ring forms the core of the catalyst and its activity is enhanced by judicious fusion of a second five-membered heterocycle to the c-edge. The catalyst performance is improved by the incorporation of an endo-cyclic electron withdrawing group adjacent to the fusion point. The organic core is effective only in the presence of an acid co-catalyst and whilst the two-component system shows potential as an enantioselective catalyst it is demonstrated that stereocontrol is a feature of the organic core and is fully independent of the choice of co-catalyst. (C) 2011 Elsevier Ltd. All rights reserved.
An investigation of structure-reactivity relationships of δ-alkenyl oximes; competitive thermal reactions leading to cyclic nitrones and/or N-unsubstituted bicyclic isoxazolidines
作者:Linda Doyle、Frances Heaney
DOI:10.1016/j.tet.2010.06.005
日期:2010.8
Thermal reactions of C-aryl δ-alkenyl oximes give N-unsubstituted bicylic lactone, lactam and pyrrolidine fusedisoxazolidines by an intramolecular oxime olefin cycloaddition pathway (IOOC) and/or cyclic nitrones by an azaprotio cyclotransfer (APT) route; a number of factors, including the nature of the aryl group, the oxime geometry and the structure of the linker between the oxime and the terminal
NH-Isoxazolo-bicycles; new molecular scaffolds for organocatalysis
作者:Linda Doyle、Frances Heaney
DOI:10.1016/j.tet.2011.01.034
日期:2011.3
A new scaffold for organocatalysis of the Diels-Alder reaction is disclosed; an isoxazolidine ring forms the core of the catalyst and its activity is enhanced by judicious fusion of a second five-membered heterocycle to the c-edge. The catalyst performance is improved by the incorporation of an endo-cyclic electron withdrawing group adjacent to the fusion point. The organic core is effective only in the presence of an acid co-catalyst and whilst the two-component system shows potential as an enantioselective catalyst it is demonstrated that stereocontrol is a feature of the organic core and is fully independent of the choice of co-catalyst. (C) 2011 Elsevier Ltd. All rights reserved.