Exaltone® (=Cyclopentadecanone) from Isomuscone® (=Cyclohexadecanone), a One-C-Atom Ring-Contraction Methodology via a Stereospecific Favorskii Rearrangement: Regioselective Application to (−)-(R)-Muscone

Treatment of cyclohexadecanone (1g; with I2 (2.2 mol‐euqiv.) and KOH in MeOH) furnished the unsaturated (Z)‐ester 2g in 83% yield, via a stereospecific Favorskii rearrangement (Scheme 1). Further treatment with 3‐chloroperbenzoic acid (m‐CPBA) afforded the unreported epoxy ester 3g (88% yield), whic...

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Bibliographic Details
Published in:Helvetica chimica acta 2012-03, Vol.95 (3), p.428-447
Main Authors: Chapuis, Christian, Robvieux, Fabrice, Cantatore, Carole, Saint-Léger, Christine, Maggi, Laurent
Format: Article
Language:English
Subjects:
(−)-(R)-Muscone
Civetone
Exaltone
Favorskii rearrangement
Regioselective synthesis
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Summary:Treatment of cyclohexadecanone (1g; with I2 (2.2 mol‐euqiv.) and KOH in MeOH) furnished the unsaturated (Z)‐ester 2g in 83% yield, via a stereospecific Favorskii rearrangement (Scheme 1). Further treatment with 3‐chloroperbenzoic acid (m‐CPBA) afforded the unreported epoxy ester 3g (88% yield), which was cleaved in 33% yield to Exaltone® (=cyclopentadecanone; 1f) with NaOH in MeOH/H2O and then HCl at 65°. This methodology was similarly extended to higher (C17) and lower (C15 to C11) cyclic ketone analogues, as well as regioselectively to (−)‐(R)‐muscone (5c) and homomuscone (5f) (Scheme 2). Olfactive properties of the corresponding macrocyclic 1‐oxaspiro[2,n]alkanes and ‐alkenes 4 and 8, resulting from a CoreyChaykovsky oxiranylation, are also presented.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.201100398