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5,6,7‐Trimethylocta‐2,5‐dien‐4‐one − A Suspected Odorant with Surprising Olfactory Properties
Author(s) -
Kraft Philip,
Denis Caroline,
Eichenberger Walter
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200106)2001:12<2363::aid-ejoc2363>3.0.co;2-e
Subject(s) - chemistry , odor , ionone , ketone , bromide , organic chemistry , isopropyl , stereochemistry
5,6,7‐Trimethylocta‐2,5‐dien‐4‐one ( 3 ) was suspected of being a trace component smelling of damascone in a crude complex reaction product. Although this trace component eventually turned out to be the constitutional isomer 2‐methyl‐3‐isopropylhepta‐2,5‐dien‐4‐one ( 4 ), the title compound 3 was found to possess even superior fruity, rosy odor characteristics, reminiscent of apples, plums, raisins and other dried fruits, and these odor characteristics are, surprisingly, due mainly to its (5 Z )‐isomer. The synthesis of 3 commenced with the preparation of 1‐ethoxyprop‐1‐yne ( 11 ) from 2‐chloro‐1,1‐diethoxyethane ( 9 ). Borontrifluoride‐catalyzed addition of methyl isopropyl ketone ( 10 ) to 11 provided ethyl 2,3,4‐trimethylpent‐2‐enoate ( 8 ), which was transformed into the target molecule 3 by Grignard reaction with propen‐1‐ylmagnesium bromide and in situ enolization. Further derivatives 13 − 16 provide more insight into the structure−odor correlation of damascone‐type odorants, and the use of 3 in perfumery is illustrated by a composition formula of a demonstration perfume.