Rearrangements of the Chrysanthenol Core: Application to a Formal Synthesis of Xishacorene B

Abstract

Reported here are substrate-dictated rearrangements of chrysanthenol derivatives prepared from verbenone to access complex bicyclic frameworks. These rearrangements set the stage for a 10-step formal synthesis of the natural product xishacorene B. Key steps include an anionic allenol oxy-Cope rearrangement and a Suaŕez directed C−H functionalization. The success of this work was guided by extensive computational calculations which provided invaluable insight into the reactivity of the chrysanthenol-derived systems, especially in the key oxy-Cope rearrangement.

Skeletal diversification by C–C cleavage to access bicyclic frameworks from a common tricyclooctane intermediate

“…[4][5][6][7] Our laboratory has been broadly interested in exploiting C-C cleavage reactions to forge new C-sp 3 bonds. [8][9][10] While not immediately obvious, the use of compounds containing more C-C bonds than a desired target compound can be greatly simplifying in synthesis-especially if the additional bonds are easily introduced en route to the target structure. 11 Cyclopropanation and [2+2] cycloaddition reactions have been a particularly effective means to arrive at intermediates of this type as these reactions can form sterically congested C-C bonds that are also highly strained and reactive.…”