Unsaturated 5 -oxazolones imidazolones

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... 

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... 

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