Subject selenium heterocycles

Benzimidazole (but not 1-methylbenzimidazole) is oxidized by permanganate, dichromate or hydrogen peroxide to imidazole-4,5-dicarboxylic acid, while napth-[l,2-d]- and -[2,3-d]-imidazoles also form products in which the heterocyclic ring remains intact, hence demonstrating its stability to these conditions. With lead peroxide benzimidazole is subject to an unusual oxidation as it forms (101), also the reaction product of lead dioxide and 2,2 -bibenzimidazolyl. In dioxane, selenium dioxide oxidizes 2-methylbenzimidazole to o-hydroxyacetanilide (66RCR122). 

Two other chapters up-date subjects covered in earlier volumes, but by different authors Selenium-Nitrogen Heterocycles, by I. Lalezari, A. Shafiee, and M. Yalpani, which up-dates the contribution by Bulka in Volume 2 on Selenazole Chemistry, and Pyrrolizidines, by D. J. Robins, which up-dates the contribution by Kochetkov and Likhosherstov in Volume 5. 

The heterocycles which are the subject of this chapter were treated in the first edition of Comprehensive Heterocyclic Chemistry (CHEC-I) <84CHEC-I(6)947> five-membered selenium-nitrogen heterocycles are found in <84CHEC-l(6)333>, whereas the tellurazoles were not included. 

Heterocyclic Chemistry is an annual publication which combines material previously reviewed in three separate SPR titles Saturated Heterocyclic Chemistry, Aromatic and Heteroaromatic Chemistry, and the heterocyclic sections of Organic Compounds of Sulphur, Selenium, and Tellurium. Heterocyclic Chemistry has now reached its fourth volume, which reviews the literature published on the subject during the period July 1981 to July 1982. 

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