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The chrysanthemumcarboxylic acids. II.—‐Esterification of the chrysanthemic acids
Author(s) -
Harper S. H.,
Reed H. W. B.
Publication year - 1951
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740020908
Subject(s) - hydrogenolysis , chemistry , yield (engineering) , raney nickel , methanol , organic chemistry , chloride , medicinal chemistry , catalysis , materials science , metallurgy
Esterification of (±)‐cis‐ and (±)trans‐chrysanthemic acids in methanolic sulphuric acid gives the expected methyl chrysanthemates together with methyl δ‐methoxydihydro‐chrysanthemates. Normal esterification of the carboxyl group is accompanied, in part, by acid‐catalysed addition of methanol to the ethylenic bond of the isobutenyl group. Methyl (±)‐cis‐δ‐methoxydihydrochrysanthemate is also formed on methanolysis of (±)‐cis‐dihydro‐chrysanthemo‐δ‐lactone. Ozonization of the methyl chrysanthemates, followed by hydrogenolysis of the ozonides, gives methyl (±)‐cis‐ and (±)‐trans‐3‐formyl‐2: 2‐dimethylcyclopropane‐I‐carboxylates in low yield. The (±)‐trans‐aldehydo‐ester is also obtained, though also in low yield, by Rosenmund reduction of (±)‐trans‐3‐carbomethoxy‐2: 2‐dimethylcyclopropane‐I‐carbonyl chloride and by Raney‐nickel hydrogenolysis of ethyl (±)‐trans‐3‐carbomethoxy‐2: 2‐dimethylcyclopropane‐I‐carbothiolate, both prepared from (±)trans‐caronic acid.