Total synthesis of atropisomeric indolosesquiterpenoids N-N bond formation: dixiamycins A and B.

N-N dimeric indolosesquiterpene alkaloids constitute a class of under-investigated architecturally intriguing natural products. Herein, we report the first chemical oxidation approach to the asymmetric total syntheses of these atropisomeric indolosesquiterpenoids through N-N bond formation. Specifically, dixiamycins A (1a) and B (1b) were prepared through a Cu(i)-mediated aerobic dehydrogenative dimerization from the naturally occurring monomer xiamycin A methyl ester (2b); this preparation also represents the first total synthesis of dixiamycin A (1a).

Total syntheses of naturally occurring antiviral indolosesquiterpene alkaloids, xiamycins C-F Csp-H functionalization.

Concise total syntheses of naturally occurring antiviral indolosesquiterpene alkaloids, xiamycin C (2a), D (2b), E (2c) and F (2d), have been achieved a late-stage oxidative δ-Csp-H functionalization of an advanced pentacyclic enone intermediate 8. This strategy takes advantage of -nitration of naturally occurring abietane diterpenoids to synthesize -bromo nitroarene derivative 11. A Suzuki-Miyaura coupling of 11 with phenylboronic acid followed by Cadogan's ring closure provided a modular approach to a carbazole ring required for a functionalized pentacyclic core of indolosesquiterpene alkaloids.

Electrocatalysis as a key strategy for the total synthesis of natural products.

Electrochemical strategies have been a powerful approach for the synthesis of valuable intermediates, in particular heterocyclic motifs. Because of the mild nature, a wide range of nonclassical bond disconnections have been achieved -generated radical intermediates in a highly efficient manner. In particular, anodic electrochemical oxidative strategies have been utilized for the total synthesis of many structurally intriguing natural products.

Pd(0)-Catalyzed Deacylative Allylations (DaA) Strategy and Application in the Total Synthesis of Alkaloids.

Natural product synthesis has been the prime focus for the development of new carbon-carbon bond forming transformations. In particular, the construction of molecules with all-carbon quaternary centers remain one of the most facinating targets. In this regard, transition-metal catalyzed processes have gained imporatnce owing to their mild nature.