Total Synthesis and Absolute Structure Assignment of (+)-Itomanallene B

The asymmetric total synthesis of (+)-itomanallene B, (−)-1,4- diepi -itomanallene B, and two additional stereoisomers, enabling the structural revision of itomanallene B, is reported. The asymmetric dihydroxylation effectively established the syn -diol centers, which guided the formation of the syn -THF ring and the installation of the allene moiety through a single biomimetic brominative cyclization. On the other hand, Tsuji-Trost cyclization was used to construct trans -THF ring followed by Corey–White–Posner reaction to install the axially chiral bromoallene. This efficient approach should provide a versatile platform for cis - and trans -2,5-disubstituted-3-oxygenated THF acetogenins and their analogues.