Corey EJ *,
Balanson RD.
Harvard University, Cambridge, USA
A Simple Synthesis of (±)-Cedrene and (±)-Cedrol Using a Synchronous Double Annulation
Process.
Tetrahedron Lett. 1973; 3153-3156
DOI:
10.1016/S0040-4039(00)79797-8
Keywords
(±)-cedrol - (±)-cedrone - sesquiterpene alcohol - Stork–Danheiser transposition -
Simmons–Smith cyclopropanation - Collins oxidation
Significance
Corey and Balanson reported a concise synthesis of (±)-cedrone, which can be readily
converted into the sesquiterpene alcohol (±)-cedrol. It features a tricyclo[5.3.1.01,5]undecane core that was assembled via a stereospecific cyclization reaction. To investigate
the stereospecificity of this annulation, Corey and Balanson separated the two diastereomers
of ketone G on preparative gas chromatography. The individual diastereomers were subjected to
cyclization conditions, furnishing either (±)-cedrone or (±)-epi-cedrone.
Comment
Enone D was prepared from enol ether B via Stork–Danheiser transposition. Reduction of the carbonyl group followed by Simmons–Smith
cyclopropanation and subsequent oxidation of the alcohol furnished ketone G with a diastereomeric ratio of 1:1. The diastereomeric mixture was treated with acetyl
methanesulfonate (H) to yield (±)-cedrone and (±)-epi-cedrone with a combined yield of 85 %.
