Enantioselective Total Synthesis of (+)‐Jungermatrobrunin A

Abstract

Ac oncise and enantioselective total synthesis of (+ +)-jungermatrobrunin A( 1), whichf eatures au nique bicyclo[3.2.1]octene ring skeleton with an unprecedented peroxideb ridge,w as accomplished in 13 steps by making use of al ate-stage visible-light-mediated Schenck ene reaction of (À)-1a,6a-diacetoxyjungermannenone C( 2). Along the way, aU V-light-induced bicyclo[3.2.1]octene ring rearrangement afforded (+ +)-12-hydroxy-1a,6a-diacetoxy-ent-kaura-9(11),16dien-15-one (4). These divergent photo-induced skeletal rearrangements support apossible biogenetic relationship between (+ +)-1,(À)-2,and (+ +)-4.

Eugenunilones A–H: rearranged sesquiterpenoids from Eugenia uniflora

“…Based on the features of these structures and the key precursor selina-1,3,4(11)-trien-8-one (9), which was also isolated from the title plant, a hypothetical biosynthetic pathway for 1-8 was proposed (Scheme 1). Firstly, the light irradiation of 9 formed the radical intermediate i, 16 and the radical addition between C-7 and C-1 led to the formation of the key radical intermediate ii with a caged tricyclic backbone. The dimerization of ii led to the generation of 1 and 2.…”