Dedicated to Professor B. C. Ranu on the occasion of his 75th birthday
A concise and scalable asymmetric synthesis of (+)-8-epigrosheimin is reported in
nine steps using only three column chromatographic purifications with an overall yield
47.0% from (R)-(–)-carvone. Two synthetic routes are evaluated by catalyst-free tandem allylboration–lactonization
of two carvone-derived aldehydes and subsequent ene cyclization, where strategy via
Lee–Lay aldehyde is found to be more effective for 8-epigrosheimin.
Key words
guaianolides - sesquiterpene lactone - tandem allylboration–lactonization - catalyst-free
- ene reaction - 8-epigrosheimin