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Exaltone ® (=Cyclopentadecanone) from Isomuscone ® (=Cyclohexadecanone), a One‐C‐Atom Ring‐Contraction Methodology via a Stereospecific Favorskii Rearrangement: Regioselective Application to (−)‐( R )‐Muscone
Author(s) -
Chapuis Christian,
Robvieux Fabrice,
Cantatore Carole,
SaintLéger Christine,
Maggi Laurent
Publication year - 2012
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201100398
Subject(s) - chemistry , stereospecificity , regioselectivity , yield (engineering) , ketone , ring (chemistry) , stereochemistry , medicinal chemistry , carbon atom , organic chemistry , catalysis , materials science , metallurgy
Treatment of cyclohexadecanone ( 1g ; with I 2 (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/H 2 O and then HCl at 65°. This methodology was similarly extended to higher (C 17 ) and lower (C 15 to C 11 ) 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.