Highly Stereoselective Intramolecular Diels–Alder Reaction of Decatrienoates Activated by t-Butoxycarbonyl, Chloro, and Sulfonyl Groups at the Terminal Position

Highly stereoselective intramolecular Diels–Alder (IMDA) reaction of decatrienoates has been achieved by using a more sterically hindered ester group, i.e., t-butoxycarbonyl, or electron-withdrawing hetero substituents, i.e., chloro and phenylsulfonyl, as terminal activating groups. A remarkable olefin isomerization of the Diels–Alder cycloadduct bearing a phenylsulfonyl group occurred upon heating it for a few hours and it was found that the isomerization can be catalyzed by Brønsted acid.