The first total syntheses of the architecturally complex atisane-type diterpenes and biogenetically related atisine-type diterpenoid alkaloids (±)-spiramilactone B, (±)-spiraminol, (±)-dihydroajaconine, and (±)-spiramines C and D are reported. Highlights of the synthesis include a late-stage biomimetic transformation of spiramilactone B, a facile formal lactone migration from the pentacyclic skeleton of spiramilactone E, a highly efficient and diastereoselective 1,7-enyne cycloisomerization to construct the functionalized tetracyclic atisane skeleton, and a tandem retro-Diels-Alder/intramolecular Diels-Alder sequence to achieve the tricyclo[6.2.2.0] ring system.

The first total syntheses of the architecturally complex atisane‐type diterpenes and biogenetically related atisine‐type diterpenoid alkaloids (±)‐spiramilactone B, (±)‐spiraminol, (±)‐dihydroajaconine, and (±)‐spiramines C and D are reported. Highlights of the synthesis include a late‐stage biomimetic transformation of spiramilactone B, a facile formal lactone migration from the pentacyclic skeleton of spiramilactone E, a highly efficient and diastereoselective 1,7‐enyne cycloisomerization to construct the functionalized tetracyclic atisane skeleton, and a tandem retro‐Diels–Alder/intramolecular Diels–Alder sequence to achieve the tricyclo[6.2.2.0] ring system.

No abstract

No abstract

No abstract