Ring-fluorinated imidazoles synthesis

Cohen, L. A., Kirk, K. L. Photochemical decomposition of diazonium fluoroborates. Application to the synthesis of ring-fluorinated imidazoles. J. Am. Chem. Soc. 1971,93, 3060-3061. 

Synthesis of Ring-Fluorinated Pyrazoles Early procedures for accessing fluoropyrazoles included the photochemical Schiemann reaction that had been developed earlier for preparation of ring-fluorinated imidazoles, as discussed above. 3-Fluoro-, 4-fluoro-, and 5-fluoro-l-methylpyrazoles were obtained in low yields (Fig. 3.65). This procedure was also used to prepare 3,4-, 4,5-, and 3,5-difluoropyrazoles. An electrochemical procedure was reported that lacked generality. ... 

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