Fm. Rivas et al., A versatile synthesis of substituted benzimidazolium salts by an amination/ring closure sequence, ORG LETT, 3(17), 2001, pp. 2673-2676
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A new method to produce benzimidazolium salts based on a successive Buchwal
d-Hartwig amination and ring closure is reported. A variety of different be
nzimidazolium salts can be prepared using this procedure. Amines that bear
an alpha -chiral group undergo the reaction to furnish chiral benzimidazoli
um salts. The salts that lack a C2 substituent on the heterocycle are readi
ly deprotonated to give nucleophilic carbenes.