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Preparation and Olfactory Characterization of the Enantiomerically Pure Isomers of the Perfumery Synthetic Galaxolide ®
Author(s) -
Fráter Georg,
Müller Urs,
Kraft Philip
Publication year - 1999
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/(sici)1522-2675(19991006)82:10<1656::aid-hlca1656>3.0.co;2-m
Subject(s) - chemistry , diastereomer , enantiomer , stereochemistry , structural isomer , alkylation , organic chemistry , catalysis
The commercially important isochromane musk odorant Galaxolide ® (=1,3,4,6,7,8‐hexahydro‐4,6,6,7,8,8‐hexamethylcyclopenta[ g ]‐2‐benzopyran; HHCB; 3 ) was separated into its diastereoisomers via the tricarbonyl( η 6 ‐cyclopenta[ g ]‐2‐benzopyran)chromium complexes 10 . Since GC/olfactometry indicated that only one enantiomer of each diastereoisomer (4 RS ,7 RS )‐ 3 and (4 RS ,7 SR )‐ 3 determines the odor characteristics of the commercial product, all four stereoisomers (4 S ,7 R )‐, (4 S ,7 S )‐, (4 R ,7 S )‐, and (4 R ,7 R )‐ 3 were synthesized by Friedel‐Crafts alkylation of 1,1,2,3,3‐pentamethylindane ( 11 ) with ( S )‐ and ( R )‐methyloxirane (( S )‐ and ( R )‐ 12 , resp.), acid‐catalyzed reaction of the resulting products with paraformaldehyde, and separation of the formed diastereoisomer pairs via the tricarbonyl( η 6 ‐cyclopenta[ g ]‐2‐benzopyran)chromium complexes 10 . The powerful musk odor of Galaxolide ® ( 3 ) was thus attributed to its (−)‐(4 S )‐isomers (4 S ,7 R )‐ and (4 S ,7 S )‐ 3 , while the (+)‐(4 R )‐isomers (4 R ,7 S )‐ and (4 R ,7 R )‐ 3 were weak to almost odorless.