2- Cyano-4 -phenylimidazole

Chloropyrazines undergo ring contraction when treated with potassium amide in liquid ammonia. The reactions resemble those of pyridines and pyrimidines, and may be useful for making 2-cyanoimidazoles despite the formation of product mixtures and low yields. For example, 2-chloropyrazine is converted into a mixture of 2-aminopyrazine (15%), imidazole (14-15%) and 2-cyanoimidazole (30-36%) [82]. In a similar experiment, 2-cyano-4-phenylimidazole (19%) can be obtained 83J. 

Under UV irradiation l-(p-nitrophenyl)-4-phenylimidazole reacts with cyanide ion to give the 2-cyano substitution product (80%) the corresponding 2-methyl analogue gave a mixture of 4-cyano (30%) and 4-hydroxymethyl (20%) products (79T1331). 

When treated with potassium artiide in liquid ammonia, suitably substituted and activated pyrimidines are converted into imidazoles, a ring eontraction which has been shown by labelling to involve cleavage of the 5,6 bond (Scheme 6.1.6). 5-Amino-4-chloro-2-phenylpyrimidine is converted under the reaction conditions into 4-cyano-2-phenylimidazole in 30-35% yield, rather better than is achieved by Comforth s method (using aminoacetonitrile with... 

The reactions of various chlorophenylpyrazines with potassium amide in liquid ammonia have been investigated in detail (827). Treatment of 2-chloro-3-phenylpyrazine with potassium amide in liquid ammonia gave only 2-amino-3-phenyl-pyrazine, but 2-chloro-6-phenylpyrazine gave 4(5)-phenylimidazole and 2-cyano-4(5)-phenylimidazole, and 2-chloro-5-phenylpyrazine gave a mixture of 2-amino-5-phenylpyrazine, 4(5)-phenylimidazole, and 2-cyano-4(5)-phenylimidazole. The 2[Pg.125]

Amino-4-chloro-2-phenylpyrimidine (62) reacts with potassium amide in liquid ammonia to form 4-cyano-2-phenylimidazole (63) 4-chloro-5-methyl-2-phenylpyrimidine (64) gives 4-ethynyl-2-phenylimidazole (65) under the same conditions.These results are somewhat surprising in... 

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