A carbamoyl-substituted nitrileoxide was generated upon treatment of easily available 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with THF (not dried); the reaction proceeded efficiently even in the absence of any special reagents and reaction conditions. The nitrileoxide caused 1,3-dipolarcycloaddition with common aliphatic nitriles or electron-rich aromatic nitriles to afford 3-functionalized 1,2
α-Nitro-δ-keto
nitriles and α-nitro-δ-keto ester were readily converted to diazabicyclo compounds having vicinal functionality upon treatment with diamines. The keto nitrile attracts the diamine nearby to an acidic hydrogen to cause the pseudo-intramolecular imination which proceeds efficiently without any catalyst at room temperature.
A nitrile oxide containing a carbamoyl group is readily generated upon the treatment of 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with water under mild reaction conditions, even in the absence of special reagents. The obtained nitrile oxide undergoes cycloaddition with dipolarophiles, alkynes and alkenes, to afford the corresponding isoxazol(in)es, which are useful intermediates in the synthesis of polyfunctionalized
A novel concept—the pseudo-intramolecular process—is applied to the synthesis of multiply functionalized heterocyclic compounds. Acidic α-nitro-δ-keto nitrile easily forms an ammonium salt upon treatment with an amine. When the amine is liberated under equilibrium, an intimate pair, namely, a nucleophilic amine and an electrophilic keto nitrile are located close to each other, is formed; thus the amine efficiently attacks a cyano group of keto nitrile. As a result of subsequent cyclization, 1,4-dihydropyridines containing an amino and a nitro group at the vicinal positions as a partial structure are afforded.
synthesizing different functionalized isoxazoles is provided. Carbamoylnitrile oxide generated from nitroisoxazolone underwent inverse electron-demand 1,3-dipolarcycloaddition with 1,3-dicarbonyl compounds in the presence of magnesium acetate that formed magnesium enolate in situ. Although electron-deficient trifluoroacetoacetate did not undergo this cycloaddition under the same conditions, conversion