Semisynthesis of macrocarpal C and analogues by selective dehydration of macrocarpal A or B.

Macrocarpals A and C are structurally related compounds that have been extracted from different Eucalyptus species. Although macrocarpal C is of biological interest, its isolation in pure form is difficult to achieve. We report herein an efficient method for the semisynthesis of macrocarpal C by selective exo-dehydration of another member of the macrocarpal family, macrocarpal A. We also report the semisynthesis of three new macrocarpal structures derived from either macrocarpal A or B.