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Total Synthesis and Absolute Structure Assignment of (+)-Itomanallene B
Rodney A Fernandes1, Ravikant S Ranjan1
1Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India.
Abstract:
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.
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