Imidazolones unsaturated

Unsaturated 5(4//)-oxazolones derived from aromatic and heterocyclic aldehydes including phthalic anhydride/ antipyrine/ " chromone/ indoles/ pyridines/" ° quinolines/" diazines/" benzoxazoles/" and benzimidazoles " " have been prepared. Reaction with nitrogen nucleophiles and subsequent cycliza-tion leads to the expected 5(477)-imidazolones. 

Amino acids " " and aminobenzoic acids " " react as nitrogen nucleophiles to effect ring opening of unsaturated 5(4//)-oxazolones. Cyclization of the intermediate acylamino amide has opened the way for the synthesis of new series of imidazolones that now incorporate a carboxylic acid moiety into the N-1 substituent. These compounds are readily further elaborated into derivatives with diverse biological activity. 

Schiff bases also react with unsaturated 5(477)-oxazolones and afford different products depending on the substituent at C-2. With 2-methyl-5(477)-oxazolones 545 as starting materials, 2-styryl-l-substituted imidazolones 546 are obtained (Scheme 7.172). ° Selected examples are shown in Table 7.43 (Fig. 7.54). 

TABLE 7.43. 2-STYRYL-l-SUBSTITUTED IMIDAZOLONES FROM REACTION OF UNSATURATED 5(4ff)-OXAZOLONES WITH SCHIFF BASES... 

On the other hand, if a 2-phenyl-5(4//)-oxazolone 547 is the starting material, A -(benzoyl)dehydroamino acid amides 548 or unsaturated imidazolones 549 are... 

Urea, thiourea, and 5-alkylisothiouronium halides have also been used as bis(nucleophiles) in reactions with unsaturated oxazolones. Reaction with urea and thiourea leads to the corresponding imidazolones. The use of... 

Methyl isobutyl ketone has become increasingly important as a chemical feedstock. The oxime is used as an antiskinning agent in oxidatively drying paints, and the peroxide is used to cure unsaturated polyester resins. Methyl isobutyl ketone is an intermediate in the preparation of imidazolones and acetal esters. It is also used to block amines (ketimines) that act as moisture-initiated latent epoxy resin hardeners. Finally, alkaline autocondensation at elevated temperature yields higher molecular mass products that are employed as fragrances and perfumes. 

---