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Synthesis of ( R )‐ and ( R )‐4‐methyl‐6‐2′‐methylprop‐1′‐enyl‐5,6‐dihydro‐2 H ‐pyran (Nerol oxide) and Natural Occurrence of its Racemate
Author(s) -
Ohloff Günther,
Giersch Wolfgang,
SchulteElte Karl H.,
Enggist Paul,
Demole Edouard
Publication year - 1980
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.19800630626
Subject(s) - nerol , chemistry , citronellol , epoxide , organic chemistry , oxide , stereochemistry , linalool , geraniol , chromatography , essential oil , catalysis
Following a known procedure, a mixture of (−)‐(2 S ,3 R )‐ and (+)‐(2 R ,3 R )‐2,3‐epoxy‐citronellols ( 5 ) was prepared from (−)‐( R )‐linalool ( 3 ) via epoxy alcohol 4 and then reduced to (−)‐( R )‐3‐hydroxy‐citronellol ( 6 ). Sensitized photooxygenation of (−)‐( R )‐diol 6 led in part to (−)‐( R )‐triol 8 which was cyclodehydrated by dilute acid to a mixture of diastereoisomeric tetrahydropyran‐4‐ols 9 and 10 . Dehydration of hydroxy ethers 9 and 10 afforded (−)‐( S )‐nerol oxide ( 11 ) and (+)‐( R )‐nerol oxide ( 12 ), respectively, with an optical purity of 91%. Nerol oxide isolated from Bulgarian rose oil (0.038%) proved to be racemic. These results shed some light on the formation of nerol oxide in plants.