A Rapid Stereocontrolled Entry to the ABCD Tetracyclic Core of Neotuberostemonine

Abstract

Four out of the five rings of the alkaloid neotuberostemonine (1) are present in the advanced precursor 2. The tetracyclic compound 2 has now been prepared in a short, linear route via lactone acid 3. A key step in the synthesis was the cuprate-mediated SN2′ ring-opening desymmetrization of the C2-symmetric bislactone 4.