Synthese und seitenselektive Diels‐Alder‐Reaktion von Homodehydroisodicyclopentadien

Synthesis and Face‐Selective Diels‐Alder Reaction of Homodehydroisodicyclopentadiene Under alkaline conditions the mesylate 6c, obtained from the tetracyclic ketone 6b fragments into the enone 8a. The latter is transformed via alcohol 9 into the homodehydroisodicyclopentadiene 3 and via tosylhydrazone 8b into the triene 4. Cyclopentadiene 3 reacts with a series of non‐acetylenic dienophiles from the sterically less hindered side to give the products 14‐17. Acetylenic dienophiles yield the adducts 19–22 in a 1:1 ratio. The UV and PE spectra of triene 4 are discussed.