A Concise Total Synthesis of (-)-Berkelic Acid

Reported here is a concise total synthesis of (-)-berkelic acid in eight linear steps. This synthesis features a Catellani reaction/oxa-Michael cascade for the construction of the isochroman scaffold, a one-pot deprotection/spiroacetalization operation for the formation of the tetracyclic core structure, and a late-stage Ni-catalyzed reductive coupling for the introduction of the lateral chain. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process. Stereocontrol of the intriguing deprotection/spiroacetalization process is supported by DFT calculations.

Automated summary

A concise total synthesis of (-)-berkelic acid is reported in eight linear steps, featuring a Catellani reaction/oxa-Michael cascade, a one-pot deprotection/spiroacetalization operation, and a late-stage Ni-catalyzed reductive coupling. Notably, four stereocenters are established from a single existing chiral center with excellent stereocontrol during the deprotection/spiroacetalization process, supported by DFT calculations.