Catalytic asymmetric synthesis of a versatile intermediate for diterpene syntheses. Regioselective olefin insertion in asymmetric Heck reactions
摘要:
We describe the details of the regioselective asymmetric cyclization of 5 to optically active 8 (95% ee), and the use of this tricyclic compound in the asymmetric synthesis of various diterpenes.
Catalytic asymmetric synthesis of a versatile intermediate for diterpene syntheses. Regioselective olefin insertion in asymmetric Heck reactions
摘要:
We describe the details of the regioselective asymmetric cyclization of 5 to optically active 8 (95% ee), and the use of this tricyclic compound in the asymmetric synthesis of various diterpenes.
The first asymmetric total synthesis of the hexacyclic veatchine-type C20-diterpenoid alkaloid (−)-garryine is presented. Key steps include a Pd-catalyzed enantioselective Heckreaction, a radical cyclization, and a photoinduced C–H activation/oxazolidine formation sequence. Of note, a highly enantioselective Heckreaction developed in this work provides efficient access to 6/6/6 tricyclic compounds
Asymmetric Allylic C–H Oxidation for the Synthesis of Chromans
作者:Pu-Sheng Wang、Peng Liu、Yu-Jia Zhai、Hua-Chen Lin、Zhi-Yong Han、Liu-Zhu Gong
DOI:10.1021/jacs.5b08477
日期:2015.10.14
An enantioselective intramolecular allylic C-H oxidation to generate optically active chromans has been accomplished under the cooperative catalysis of a palladium complex of chiral phosphoramidite ligand and 2-fluorobenzoic acid. Mechanistic studies suggest that this reaction commences with a Pd-catalyzed allylic C-H activation event and then undergoes asymmetric allylic alkoxylation. The synthetic significance of the method has been embodied by concisely building up a key chiral intermediate to access (+)-diversonol.