| Abstract
| - Wang resin-bound intermediates derived from Fmoc-l-phenylalaninal and Fmoc-l-valinal, and aresin supported Horner−Wadsworth−Emmons reaction, were treated with cinnamaldehydederivatives, acetic acid, and borohydride to give secondary amines which were subsequentlybenzoylated to afford various derivatives of 3. Heating 3 at 95 °C induced cycloaddition reactionsand produced 4 as the major product. Compounds 3 which were derived from 4-methoxycinnamaldehyde were more reactive, but did not give 4 and 4−7g. The direct cleavage of 3b using TFA ledto the isolation of cycloaddition−demethylation product 10. The derivative of 3, which containedan electron-withdrawing nitro group on the phenyl ring, produced a single diastereomer of 4. TheDiels−Alder cycloaddition between two electron-deficient counterparts showed similar reactivityto that of the reactions which have a normal complementary electron-demand.
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