Divergent Total Synthesis of Atisane‐Type Diterpenoids

Abstract

Atisane-type diterpenoids are the principal constituent of tetracyclic C -diterpenoids, widely isolated from the plant kingdom with varying degrees of structural complexity and pharmacological activity. The tetracarbocyclic system with the unique bicyclo[2.2.2]octane skeleton of this natural product family has generated interest within the synthetic community. Divergent total synthesis is an effective tactic to synthesize several atisane-type diterpenoids using structural interconversion from a common intermediate. This account summarizes the divergent total synthesis of atisane-type diterpenoids.

Asymmetric Divergent Synthesis of ent-Kaurane-, ent-Atisane-, ent-Beyerane-, ent-Trachylobane-, and ent-Gibberellane-type Diterpenoids

“…During such a bioprocess, ent -beyeranyl cation I , which may result from cascade cyclization of GGPP via ent -copalyl diphosphates ( ent -CPP), plays a central role in a series of enzyme-catalyzed transformations, producing a diverse array of ent -beyerane-, ent -trachylobane-, ent -kaurane-, ent -atisane-, and ent -gibberellane-type cores and beyond. Due to their structural diversity and biological significance, chemical synthesis of polycyclic diterpenoids has always been an important theme in the synthetic community, − and numerous remarkable total syntheses of C8-ethano-bridged diterpenoids have been documented since Ireland and co-workers reported the first total synthesis of (±)-kaurene . Despite great progress in tetracyclic diterpenoid synthesis, however, the development of unified strategies toward collective construction of biogenetically related C8-ethano-bridged diterpenoid skeletons is still limited .…”

Total Synthesis of Terpenoids Employing a “Benzannulation of Carvone” Strategy: Synthesis of (−)-Crotogoudin

“…In this Communication, we report our initial investigations into developing this potentially unifying strategy, which has afforded the frameworks of several terpenoid secondary metabolites via short diastereoselective sequences. The virtues of this approach are borne out in a short, enantiospecific total synthesis of the ent- 3,4- seco -atisane diterpenoid (−)-crotogoudin ( 1 ) in 13 steps from ( S )-carvone.…”