Abstract:
The first asymmetric total synthesis of (+)-dihydroitomanallene b and its two diastereomers, and the formal synthesis of (−)-kumausallene are reported. The synthesis of the former was completed in 18 steps from 1,4-butanediol (3.4% overall yield), with diastereoselective tsuji-trost cyclization to access cis-2,5-disubstituted-3-oxygenated thf scaffold and a corey-white-posner reaction to install the bromoallene moiety as the key steps. In addition, the enantioselective formal total synthesis of (−)-kumausallene involving the key tsuji-trost cyclization is also realized. © 2022 the royal society of chemistry.