Diene syntheses dienamines

Acyclic dienamines are relatively unstable, but very reactive towards electron-poor dienophiles as describe in a review article (1984). A more recent example shows the preparation of sterically encumbered 1-amino-1,3-diene (125) and its, nevertheless, efficient and highly stereoselective [4 + 2] cycloaddition to dimethyl fumarate (Scheme 32). Elimination of pyrrolidine, by heating the non-iso-lated cycloadduct with acetic anhydride, afforded hexahydronaphth ene (126), a key intermediate for a synthesis of drimane-type sesquiterpenes. 

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