5-Methyl-3-isoxazolecarboxylic acid

Chemical Name 5-Methyl-3-isoxazolecarboxylic acid 2-benzyIhydrazide Common Name -Structural Formula ... 

Methyl-3-isoxazolecarboxylic acid, M-30084 5-0-Methylleridol, in D-20125 A-Methylleukotriene C4, in L-10046 24a-Methyllophenol, in M-10056... 

Chemical Name B-Methyl-S-isoxazolecarboxylic acid 2-benzvlhydrazlde Common Name —... 

Isocarboxazid Isocarboxazid, 2-benzylhydrazid-5-methyl-3-isoxazolecarboxylate (7.2.6), can be synthesized from acetylacetone, which on nitrosation with nitrous acid gives 5-methyl-isoxazol-3-carboxyhc acid (7.2.2). Esterification of this product gives the ethyl ester of 5-methyl-isoxazol-3-carboxyhc acid (7.2.3). The synthesized ester (7.2.3) is further reacted with benzylhydrazine, to give isocarboxazide (7.2.6), or with hydrazine, which forms 5-methyl-isoxazol-3-carboxylic acid hydrazide (7.2.4). Reacting the latter with benzaldehyde gives hydrazone (7.2.5), which is further reduced to the isocarboxazide (7.2.6) [46,47]. 

The reaction mixture is poured into a 4-1. separatory funnel and washed with 1 1. of cold water. The chloroform layer is then washed with 6N aqueous hydrochloric acid until the amine bases are removed and the wash remains acid (Note 4). The chloroform extracts are washed successively with 5% aqueous sodium hydroxide (Note 5) and saturated brine, dried over anhydrous magnesium sulfate, and filtered. The solvent is removed with a rotary evaporator, and the product is distilled under vacuum to yield 122-130 g. (68-71%) of ethyl 3-ethyl-5-methyl-4-isoxazolecarboxylate, b.p. 72° (0.5 mm.), n23d 1.4615 (Note 6). 

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