5805-32-3Relevant academic research and scientific papers
A New Synthetic Method for the 2-Substitution of N-Unsubstituted Benzimidazoles: Formaldehyde as a Versatile Protecting Agent for Heterocyclic NH
Katritzky, Alan R.,Akutagawa, Kunihiko
, p. 2949 - 2952 (2007/10/02)
N-Unsubstituted benzimidazoles 1 are readily converted in a one-pot sequence into 2-substituted derivatives 2 with good overall yields.N-Protection with formaldehyde and lithiation with lithium N,N-diisopropylamide (LDA), n-butyllithium, or tert-butyllithium gives the dilithiohemiaminals 6, which readily react with a range of electrophiles at the 2-carbon.The 2-substituted 1-(lithioxymethyl)benzimidazoles 7 undergo smooth acid-catalyzed dehydroxymethylation under mild conditions to give N-unsubstituted 2-substituted benzimidazoles 2.
Synthesis of 2-Substituted Imidazoles and Benzimidazoles and of 3-Substituted Pyrazoles by Lithiation of N-(Dialkylamino)methyl Heterocycles
Katritzky, Alan R.,Rewcastle, Gordon W.,Fan, Wei-Qiang
, p. 5685 - 5689 (2007/10/02)
The lithiation of N-(dialkylamino)methyl (aminal) derivatives of imidazole, benzimidazole, and pyrazole (themselves readily available from parent heterocycles, formaldehyde, and a secondary amine) occurs smoothly at 2-, 2-, and 5-positions, respectively, upon treatment with n-butyllithium in ether or tetrahydrofuran.Reaction with electrophiles, and subsequent facile acid-catalyzed hydrolysis of the protecting group, provides 2-substituted imidazoles, 2-substituted benzimidazoles, and 3(5)-substituted pyrazoles in good overall yields.
Practicable Syntheses of 2-Hydroxymethyl-substituted Benzimidazoles and 2-Formylbenzimidazole
Ooi, Hong Chin,Suschitzky, Hans
, p. 2871 - 2876 (2007/10/02)
N-Protection of benzimidazole by a diethoxymethyl group, as in , allows exclusive lithiation at the 2-position.This protected anion can be made to react with various electrophiles (e. g. ketones, aldehydes) to yield the corresponding 2-hydroxymethylbenzimidazoles (1).Facile deprotection occurs with acid.Two practicable syntheses of 2-formylbenzimidazole are also described and an indirect route to benzimidazole-2-alcohols is discussed.
