Trifluoroacetaldehyde ethyl imidazole

Table 1. Thermal Condensation of Substituted Imidazoles with Trifluoroacetaldehyde Ethyl Hemiacetal [5]...

One of the popular and widely used methods for the synthesis of 2-trifluoromethylimidazole involves the Radziszewski reaction (Debus-Radziszewski reaction) [2a]. Following the Davidson s modifications (using ammonium acetate in acetic acid instead of ammonia in alcohol) [13a], Lombardino and Wiseman prepared a series of 2-trifluoromethylimidazoles via the condensation of a-dicarbonyl compounds and trifluoroacetaldehyde ethyl hemiacetal (Scheme 4) [13b]. The reaction presumably proceeds via the formation of a diimide intermediate that subsequently undergoes condensation with the aldehyde to afford the final product. An anhydrous condition is highly recommended for better yields of imidazoles. 

The condensation of l-phenyl-3,3,3-trifluoro-l,2-propanedione monohydrate with various aldehydes in the presence of ammoninm acetate afforded the corresponding 4-phenyl-5-trifluorDmethylimidazoles (Scheme 31) [44]. For the preparation of 2,5-bis(trifluoromethyl)imidazoles, trifluoroacetaldehyde ethyl hemiacetal was used in excess instead of the aldehydes. The prerequisite diketone, that was isolated as its monohydrate, was prepared from the corresponding ketone using SeOa-... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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