Short Synthesis of a Taxane-AB-Fragment with a Spiro-Cyclopropyl Group

Abstract

An efficient synthesis of the taxane-AB-fragment with a spiro-cyclopropyl group 2 was accomplished. The synthetic strategy toward this AB-fragment involved a cyclopropanation of hydroazulenone 1, a Grignard addition, and an acid catalyzed cyclopropylcarbinyl-rearrangement.

Rearranged Dichapetalin‐Type Triterpenoids with Cytotoxic Activity from Dichapetalum gelonioides

“…[ 17 ] Through a base‐driven rearrangement involving a subsequent loss of the Enz‐X ‐ moiety, [ 17 ] intermediate III would yield IV with a newly formed cyclopropane ring. The V would originate from IV via a ring expanding reaction by free radical mechanism, [ 18‐19 ] which was then converted to compound 3 through an enzyme‐mediated O ‐methylation reaction. [ 20 ] The V would yield compounds 1 and 2 with a 2‐phenylpyran moiety by an oxidation reaction of C‐29, followed by an acid‐triggered intramolecular electrophilic addition reaction of VI .…”

Norcyperone, a Novel Skeleton Norsesquiterpene from Cyperus rotundus L.

“…A novel skeleton norsesquiterpene, norcyperone, together with three known compounds 2 - 4 were isolated from the rhizomes of C. rotundus L. Although a 8,11,11-trimethylbicyclo[5.3.1]undecane has been reported as a synthetic intermediate derived in the course of synthesis of the taxane-AB-fragment with a spiro-cyclopropyl group [ 14 ], this is the first report of a 8,11,11-trimethyl-bicyclo[5.3.1]undecane-3-one type norsesquiterpene with a tetrahydrofuran ring at C-5 and C-8. Compounds 2 - 4 were isolated from the genus Cyperus for the first time.…”