posted on 2021-11-30, 13:36authored byMinami Odagi, Taisei Matoba, Kazuo Nagasawa
We describe enantioselective total
syntheses of cepharatines A-D,
members of the hasubanan alkaloid family, which feature an unusual
tetracyclic skeleton including an azabicyclo[3.3.1]nonane motif. A
key reaction is a regio-divergent oxidative phenolic coupling reaction
that affords the tricyclic core structure of hasubanan with different
substitution patterns on the A-ring, including the all-carbon quaternary
stereogenic center at C13, in a single step. The characteristic tetracyclic
azabicyclo[3.3.1]nonane motif was constructed by means of a bioinspired
cascade reaction involving the retro-aza-Michael reaction/hemiaminal
formation.