Highly Efficient and Scalable Synthesis of Clionamine D

Herein we describe
an efficient and scalable synthesis of clionamine D (4), a special member with autophagy bioactivity and an unprecedented
spirobislactone side chain in the novel aminosteroid clionamines.
This synthesis features a quick access to α-methylene-γ-lactone 8 and a Mn­(OAc)3-mediated radical [3 + 2] reaction
to assemble the unique spirobislactone unit. Clionamine D (4) can also serve as a key synthetic precursor to other clionamine
members.