Synthetic studies towards furosesquiterpenoids: total synthesis of (±) desmethylpallescensin-A, (±) isopallescensin-A and (±) isopallescensin-1

A new approach for a short and efficient synthesis of common cyclohexenone intermediate towards the total synthesis of some furosesquiterpenes and their analogues are described. Regioselective alkylation of Hagemannʹs ester with 2/3-furyl-2-ethyl bromide followed by hydrolysis cum in situ decarboxylation and 1,4-addition with Gilmanʹs reagent produced the cyclohexanone derivatives which have been utilized for total synthesis of (±) isopallescensin-A, (±) 10-desmethylpallescensin-A, (±) 5-desmethyl-4,5-dehydromicrocionin-1 and (±) isopallescensin-1.