Total Synthesis of (±)-Ishwarane

Key words

(±)-ishwarane - Robinson annulation - conjugate addition - Grignard addition - cyclopropanation - carbene C–H insertion

Significance

Ishwarane is a sesquiterpene featuring a carbon skeleton with an intriguing tricyclo[3.2.1.0^2,7]octane core. After the first total synthesis of ishwarane reported by Kelly and co-workers in 1970/1971 (J. Chem. Soc. D 1970, 1102; J. Chem. Soc. D 1971, 479), Cory and co-workers present a highly efficient six-step sequence to the natural product exploiting carbon atom insertion.

Comment

Previously reported octalone D is rapidly elaborated into cis-decaline F through conjugate addition, Grignard addition, and dehydration. A cyclopropanation and C–H insertion cascade via putative carbene intermediate G yields (±)-ishwarane.

Publication History

Article published online:
17 May 2022