Chemistry of α-Haloaldehyde. VI. Reaction of 2-Chloro-2-methylpropanal with Benzoylacetonitrile in the Presence of Potassium Carbonate

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Abstract
The reaction of 2-chloro-2-methylpropanal with benzoylacetonitrile in aqueous K2CO3 has been studied. When 2-chloro-2-methylpropanal was added to a stirred suspension of benzoylacetonitrile in aqueous K2CO3, 2-hydroxy-3,3-dimethyl-4-cyano-5-phenyl-2,3-dihydrofuran (7) was obtained. The oxidation of 7 with CrO3gave α,α-dimethyl-β-cyano-γ-phenyl-Δβ,γ-butenolide (8). When benzoylacetonitrile was added to a suspension of 2-chloro-2-methylpropanal in aqueous K2CO3 stirred beforehand for 60 min, the reaction proceeded in a different manner to give the enol tautomer (9b) of 2,4-dibenzoyl-3-(α-hydroxyisopropyl)glutaronitrile (9a) at room temperature, and 2,2-dimethyl-3-(α-carbaminophenacyl)-4-cyano-5-phenyl-2,3-dihydrofuran (11) at 80–90 °C. The alkaline hydrolysis of the nitrile 9 conducted at 70 °C also afforded the amide 11. The nitrile 9 eliminated one mol of benzoylacetonitrile on treatment with H2SO4 to afford 2,2-dimethyl-3-hydroxy-4-cyano-5-phenyl-2,3-dihydrofuran (12). Chromic acid oxidation of 12 gave 2,2-dimethyl-3-oxo-4-cyano-5-phenyl-2,3-dihydrofuran (14), which can be derived from bullatenone in two steps. Structures of compounds 11, 12, and 14, which all possess 2,2-dimethyl-4-cyano-5-phenyl-2,3-dihydrofuran ring, have been confirmed and well correlated by both chemical transformations and spectral data.
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