Isolation and chemistry of clerodane diterpenes from Dodonaea ceratocarpa

Total Synthesis of Huperzine Q

“…We found that a ring contraction reaction of an epoxyketone was effective for this purpose . The silyl enolate moiety in 17 was oxidized with DDQ to afford enone 18 . Sequential cleavage of the Boc and TBDPS groups gave hydroxy nosylamide 19 , which, upon subjection to the Mitsunobu reaction conditions with di­(2-methoxy­ethyl) azodicarboxylate (DMEAD), underwent cyclization to produce the tricyclic compound 20 .…”