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.