Total Synthesis of (+)-Spectinabilin, Taiwaniaquinoids, Synthetic Progress toward Aspergillin PZ, and Synthesis of a Photoswitchable Agonist of Glutamate Receptor-dMAG
A new and highly enantioselective synthetic route to γ-methoxypyranone addressed the long unsolved racemization problem in literature. A concise total synthesis of (+)-Spectinabilin was achieved with this method in 10 linear steps. Concept of kinetic resolution with temporary stereocenter was used to improve the enantiomeric excess.
A new variant of Nazarov reaction, aromatic Nazarov triflation was discovered which allowed rapid access of polycyclic ring skeleton. The triflation product, indene triflate, was further elaborated with modern palladium cross coupling methods in the total syntheses of many taiwaniaquinoid natural products. Also, the triflation method worked well with electron rich and neutral substrates and was not compatible with electron deficient substrates.
Effort toward total synthesis of Aspergillin PZ was described. The biomimetic synthetic hypothesis was pursued. Synthesis of all components was achieved. Future work would be focused on mild reaction condition to bring all components together to for the key intermediate for Aspergillin PZ.
Finally, based on the similar principle of previous work in our group, a photoswitchable agonist for metabotropic glutamate receptors was designed and synthesized. Preliminary results confirmed the agonist activity and reversible isomerization with radiation of light of different wavelengths. Further studies are under investigation under collaboration.