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 stereospecificFavorskiirearrangement (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