5-amino-4-cyano-2-substituted oxazoles

Freeman s group ° prepared a series of 5-amino-4-cyano-2-substituted oxazoles 517 from carboxylic acids and aminomalononitrile tosylate (AMNT) (Scheme 1.140). Presumably, AMNT is acylated by a carboxylic acid using DCC, which produces an intermediate A-acylamino nitrile 516 that is cyclized under the reaction conditions to yield 517. The yields of 517 are fair to excellent, and the reaction tolerates a wide variety of functional groups. This further extended the scope of their earlier work. ° Representative examples are shown in Table 1.35. 

TABLE 1.35 5-AMINO-4-CYANO-2-SUBSTITUTED OXAZOLES FROM AMINOMALONONI-TRILE TOSYLATE AND CARBOXYLIC ACIDS, 110... 

Acylation of /3,/3-dichloro-a-aminoacrylonitrile (126, an enamine, obtained by the base-catalyzed addition of hydrogen cyanide to dichloro-acetonitrile) followed by treatment with amines (primary or secondary) or hydrazines provides a new method of synthesis of 4-cyano-5-(N-substituted amino)-oxazoles (127) in almost quantitative yields.185... 

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