A Versatile Synthesis of Substituted Benzimidazolium Salts by an Amination/Ring Closure Sequence

Abstract

[reaction: see text]. A new method to produce benzimidazolium salts based on a successive Buchwald-Hartwig amination and ring closure is reported. A variety of different benzimidazolium salts can be prepared using this procedure. Amines that bear an alpha-chiral group undergo the reaction to furnish chiral benzimidazolium salts. The salts that lack a C2 substituent on the heterocycle are readily deprotonated to give nucleophilic carbenes.

Synthesis and oxidation of (benzimidazolylidene)Cr(CO)5 complexes

“…4-Dimethylaminophenyl and mesityl (2,4,6-trimethylphenyl) groups are selected as a substituent on the nitrogen. 1,2-Dibromobenzene was treated with N,N 0 -dimethyl-1,4-phenylenediamine in the presence of t-BuONa, 10 mol% of Pd(OAc) 2 , and 2,2 0 -bis(diphenylphosphino)-1,1 0 -binaphthyl (BI-NAP) in toluene [10,11], to give 3 in 90% yield. The mesityl derivatives 4 was also obtained in the similar manner in 86% yield.…”

Anellated N‐Heterocyclic Carbenes: 1,3‐Dineopentylnaphtho[2,3‐d]imidazol‐2‐ylidene: Synthesis, KOH Addition Product, Transition‐Metal Complexes, and Anellation Effects

“…One such variation is anellation by aromatic carbo-or heterocycles; this is currently gaining increasing interest. [7][8][9][10][11][12][13][14] Examples are NHCs 1-6. The electron density Abstract: Two novel anellated N-heterocyclic carbenes (NHC), 1,3-dineopentylnaphtho[2,3-d]imidazol-2-ylidene, and 1,3-dineopentyl-2-ylidoimidazolo [4,5-b]pyridine were obtained by reduction of the respective thiones with potassium, the former also by deprotonation of the corresponding naphthimidazolium hexafluorophosphate by using excess KH in THF.…”

The first enantiomerically pure thiadiazol-3-one 1-oxide and thiatriaza-indene 3-oxide systems chiral at the sulfur atom

“…Diver has reported the use of C 2 symmetric carbenes based on a benzimidazole structure, 10 and this prompts us to describe our own results in this area. Such a design of ligand is attractive because both of the enantiomers are, in principle, available, and because the ligands can be readily accessed through a short synthetic sequence; for example, the 1,2-bis-α-methylbenzylaniline 11 was easily prepared as shown in Scheme 3.…”