57. Synthesis and Structure Revision of Dichrocephones A and B
V. M. Schmiedel, Y. J. Hong, D. Lentz, D. J. Tantillo, M. Christmann
Herein, we report the first enantioselective synthesis of dichrocephones A and B, cytotoxic triquinane sesquiterpenes with a dense array of stereogenic centers within a strained polycyclic environment. Key features include the application of a catalytic asymmetric Wittig reaction followed by stereoselective functio-nalization of the propellane core into a pentacyclic intermediate. Double reductive ring cleavage yielded the proposed structure of dichrocephone A. Mismatching spectroscopic data of our synthetic material and the natural isolate led us to revise the proposed configuration based on biosynthetic considerations and NMR calculations. Implementation of these findings culminated in the synthesis of dichrocephone A and B.