25° SEMINARIO QUÍMICA ORGÁNICA IQUIR 2021

SEMINARIO QUÍMICA ORGÁNICA 29-11-21

EXPOSITOR: Lic. Nadia L. Martiren

TÍTULO: "Enantioselective Total Synthesis of (+)-Heilonine".

FUENTE: Kyle J. Cassaidy and Viresh H. Rawal, J. Am. Chem. Soc. 2021, 143, 16394-16400.

DÍA, HORA y LUGAR: Lunes 29 de noviembre de 2021, 18:00 h, Plataforma MEET GOOGLE.

Link: meet.google.com/bfh-poxv-bso

RESUMEN: Chemical transformations that rapidly and efficiently construct a high level of molecular complexity in a single step are perhaps the most valuable in total synthesis. Among such transformations is the transition metal catalyzed [2 + 2 + 2] cycloisomerization reaction, which forges three new C–C bonds and one or more rings in a single synthetic operation. We report here a strategy that leverages this transformation to open de novo access to the Veratrum family of alkaloids. The highly convergent approach described herein includes (i) the enantioselective synthesis of a diyne fragment containing the steroidal A/B rings, (ii) the asymmetric synthesis of a propargyl-substituted piperidinone (F ring) unit, (iii) the high-yielding union of the above fragments, and (iv) the intramolecular [2 + 2 + 2] cycloisomerization reaction of the resulting carbon framework to construct in a single step the remaining three rings (C/D/E) of the hexacyclic cevanine skeleton. Efficient late-stage maneuvers culminated in the first total synthesis of heilonine (1), achieved in 21 steps starting from ethyl vinyl ketone.