Internal Diels−Alder Cycloaddition with a Z-Dienophile: Synthesis of (±)-α-Oplopenone
摘要:
The preparation of the Z-triene 3 is described. Internal Diels-Alder cycloaddition of 3 proceeds smoothly in the presence of BF3. OEt2 to give 2. Ketone 2 is converted by epimerization, carbonyl extrusion, and homologation to the sesquiterpene (+/-)-alpha-oplopenone (1).