Benzimidazole 2-alkylamino

The reaction of /V-alkylamino[ 1,2,4]thiadiazolo[2,3- ]benzimidazoles 217 with arylmethyl bromides gives the iV-alkylated derivatives 218 (unreported yields) (Equation 22) <1998BMCL505>. 

Oxidation of Aralkyl,iV -(2-benzimidazolyl)thioureas 294 with hydrogen peroxide, in the presence of sodium hydroxide, gives 2-alkylamino[l,2,4]thiadiazolo[2,3- ]benzimidazoles 139 (Equation 45) <1999JHC991>. 

Only condensed imidazoles will enter into the Chichibabin reaction.406 Sulfo groups on C-2 of benzimidazoles are replaced by chloro,407 cyano,408 hydroxy,409 410 and alkylamino groups,411 and the... 

The 2-halo-substituted benzimidazoles, then, more or less readily react with ammonia, amines and hydrazines (80AHC 27)241,70AHC(12)103,74CRV279), It is likely that the formation of the 2-pyridinium compound (123) when cycloheptimidazolin-2(l//)-one reacts with phosphoryl chloride in pyridine occurs via the 2-chloro intermediate (Scheme 56). The sulfur function of benzimidazole-2-sulfonic acid can be displaced by amino or alkylamino groups. 

Photolysis of indazole converts it into benzimidazole in 27% yield. 2-Alkylindazoles form 1-alkylbenzimidazoles under the same conditions, but 1-alkylindazoles give 2-alkylamino benzonitriles [12, 13], The reactions appear to have little synthetic significance. 

Irradiation of 3-[o-(alkylamino)phenyl]-5-methyl-l,2,4-oxadiazole 1507 leads to concomitant formation of benzimidazoles 1509 and indazoles 1508, presumably arising from a common photolytic species, as shown in Scheme 390 <1996JOC8397>. 

Substituted imidazo/benzimidazo[2,l- ]quinazolinones could be synthesized from (l//-imidazol-l-yl)[2-(alkylamino)phenyl]methanones and (l//-benzimidazol-l-yl)[2-(alkylamino)phenyl]-methanones catalyzed by CuCl in the absence of hgand using air as the oxidant (Scheme 8.105). The method is tolerant toward functional groups in the substrates, and a range of 5-substituted imidazo/benzimidazo[2,l- ]quinazolinones could be obtained in moderate to good yields. A C(sp )-H bond was activated to form a new C-N bond [179]. 

---