Synthesis of 2,4-dimethyl-6-oxo-2,4-heptadienoic acid derivatives from 2,4,6-trimethylpyrylium salts |
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Authors: | Alexandru T Balaban Adriana TudoseMiron T Caproiu |
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Institution: | a Texas A&M University at Galveston, 5007 Avenue U, Galveston, TX 77553, USA b Center of Organic Chemistry, ‘C.D. Nenitzescu’ of the Romanian Academy, Spl. Independentei 202B, 71141 Bucharest, Romania |
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Abstract: | Reaction 2,4,6-trimethylpyrylium salts with sodium cyanide in boiling water yielded the bicyclic lactone 1,3,5-trimethyl-6,8-dioxabicyclo3.2.1]oct-2-en-7-one (6) along with a series of stereoisomers of 2,4-dimethyl-6-oxo-2,4-heptadienonitrile (5), which were the sole products when the reaction was carried out at room temperature. Compound 6, along with 3,5-dimethylphenol (7), was also obtained by refluxing 5 briefly in aqueous sodium hydroxide. However, when 5 was refluxed for a prolonged period in aqueous sodium acetate, 3,5-dimethyl-5-(2-oxopropyl)-furan-2-one (8), along with some 7, was generated instead. Compound 8 could also be produced from 6 on prolonged refluxing with aqueous sodium acetate, indicating that 6 was the kinetically-controlled and 8 the thermodynamically-controlled product. |
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Keywords: | stereoisomers 2 4 6-trimethylpyrylium salts aqueous sodium acetate lactones |
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