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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
Author(s) -
Sche Pietro,
Fossa Paola,
Menozzi Giulia
Publication year - 1991
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570280247
Subject(s) - chemistry , sodium methoxide , hydrochloric acid , hydrolysis , methanol , hydroxylamine , hydrochloride , acetic acid , hydroxylamine hydrochloride , sodium ethoxide , alkaline hydrolysis , organic chemistry , yield (engineering) , bromide , medicinal chemistry , acid hydrolysis , ethanol , materials science , metallurgy
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‐hydroxyfuro[3,4‐ d ]isoxazol‐6‐(4 H )‐one.