Concise syntheses of 3-methylenetetrahydrofuran-2-one derivatives and related systems
Abstract
Using the Shapiro reaction, the title compounds were prepared in ‘one pot’ from the condensation of two ketones, or an aldehyde and a ketone, with carbon dioxide. For example, acetone 2,4,6-tri-isopropylbenzenesulphonylhydrazone was treated in sequence with n-butyl-lithium (–50 °C), acetone (–50 °C), n-butyl-lithium (–78 to 0 to –78 °C), carbon dioxide (–78 °C), and trifluoroacetic acid (25 °C) to give 5,5-dimethyl-3-methylenetrahydrofuran-2-one. The reaction was extended to prepare derivatives of 3-methylenetetrahydropyran-2-one and 3,5-dimethylenetetrahydrofuran-2-one.
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