Catalyzed Aminolysis of Acetoacetanilides

A commercially available acid zeolite has also been reported to be an efficient catalyst in the completely salt-free production of ureas. Reaction of aromatic amines with ethyl acetoacetate 1105 in the presence of HY zeolite HSZ-360 (1 g of zeolite/ 20 mmol of amine) under solvent-free conditions gives symmetrical diarylureas 1107 in good yields (58-77%) and with excellent selectivity (93-96%) through a straightforward procedure (route A). Acetone, ethanol, and traces of acetoacetani-hdes are the sole by-products [793]. 

This type of synthesis cannot be applied to aliphatic amines because these compounds undergo nucleophilic attack at the keto group to produce ) -alkylaminocro-tonic acid ethyl esters as the main products. 

However, symmetrical aliphatic ureas 1108 can be successfiilly prepared (65-95% yield) by reacting primary aliphatic amines with acetoacetanilide 1106 over the same zeolite catalyst (route B) (Table 4.35) [794]. 

Ar = 4-MeOC6H4, CeH -MeC6H4, 4-MeC6H4, 4-CIC6H4 R = alkyl, cycloalkyl 

In both cases, the zeolite catalyst can be recovered and reused for at least five runs without a discernible decrease in its activity. 

---