a b s t r a c tThermal reactions of C-aryl d-alkenyl oximes give N-unsubstituted bicylic lactone, lactam and pyrrolidine fused isoxazolidines 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 alkene, contribute to the competition.

a b s t r a c tA new scaffold for organocatalysis of the DielseAlder 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.

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