- Reaction of 2-Dimethylaminomethylene-1,3-diones with Dinucleophiles. X. Synthesis of 5-Substituted Ethyl or Methyl 4-Isoxazolecarboxylates and Methyl 4-(2,2-Dimethyl-1-oxopropyl)-5-isoxazolecarboxylate
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Reaction of ethyl or methyl 2-dimethylaminomethylene-3-oxoalkanoates with hydroxylamine hydrochloride in methanol solution afforded in high yields the relative esters of 5-substituted 4-isoxazolecarboxylic acids II.These esters were hydrolyzed generally with concentrated hydrochloric acid-acetic acid mixtures to the corresponding carboxylic acids in satisfactory yields.Ethyl or methyl esters II isomerized with sodium ethoxide or methoxide, respectively, to the corresponding esters or hemiesters of 2-cyano-3-oxoalkanoic acids generally in excellent to satisfactory yields.Reaction of methyl 5,5-dimethyl-3-dimethylaminomethylene-2,4-dioxohexanoate with hydroxylamine hydrochloride afforded in moderate yield methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate, which was converted by acid hydrolysis as above to 4-t-butyl-4-hydroxyfuroisoxazol-6-(4H)-one.
- Schenone, Pietro,Fossa, Paola,Menozzi, Giulia
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p. 453 - 457
(2007/10/02)
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