The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Fission or me benz-α,β-isoxazole ring》. Authors are Lindemann, Hans; Cissee, Hans.The article about the compound:1,2-Benzisoxazolecas:271-95-4,SMILESS:C12=CC=CC=C1ON=C2).COA of Formula: C7H5NO. Through the article, more information about this compound (cas:271-95-4) is conveyed.
Me 6-nitrobenzisoxazole-3-carhoxylate (Borsche, C. A. 6, 2422), when heated with slightly diluted H2SO4 20 mins. on the H2O bath, gives 6-nitrobensisoxazole-3-carboxylic acid(I), m. 189-90° (evolution of CO2); alk. hydrolysis gives a I which crystallines with 1 H2O, lost in vacuo over P2O5. I and N2H4.H2O in EtOH give the corresponding hydrazide, m. 170° (Ac derivative, m. 213-4°), converted by HNO2 into the corresponding azide, m. 135° (decomposition). Decomposition of this with AcOH gives di [6-nitrobenzisoxazole-3]carbamide, m. 342°, while with Ac2O and a little concentrated H2SO4 there results a mixture of 6-nitro-3-acetamido-, m. 230° (not sharp), and 6-nitro-3-diacetamidobenzisoxazole, m. 133°. Warming either Ac derivative with 2 N NaOH gives 3,4′-nitro-2′-hydroxyphenyl-5-methyl-1,2,4-oxdiazole, m. 124° (Ac derivative, m. 162°), thus demonstrating fission of the isoxazole ring and subsequent reaction between the oximino and acetamido groups. Hydrolysis of the Ac derivatives with fairly concentrated H2SO4 gives 6-nitro-3-aminobenzisoxazole m. 234° converted by HNO2 into 6-nitro-3-hydroxybenzisoxazole(III), m. 85-8° (decomposition). Treating III with AcOH or II with HNO2 in AcOH gives 4-nitro-2-hydroxybenzacetylhydroxamic acid, m. 184°, then at 241°, hydrolyzed by 10% NaOH to the corresponding hydroxamic acid, m. 214°. Either acid, heated with MeOH-KOH, gives 6-nitrobenzoxazol-2-one, m. 241°. The mechanism of the fission is explained by assuming the addition of 1 mol. H2O: If the group R has no depressant action (e. g., HO, NHAc) on the conjugated system fission occurs, but when R depresses the conjugation (e. g., alkyl, NH2) fission is inhibited.
Compounds in my other articles are similar to this one(1,2-Benzisoxazole)COA of Formula: C7H5NO, you can compare them to see their pros and cons in some ways,such as convenient, effective and so on.
Reference:
Highly efficient and robust molecular ruthenium catalysts for water oxidation,
Catalysts | Special Issue : Ruthenium Catalysts – MDPI