ChemInform Abstract: NUCLEOPHILIC ADDITION TO 2H‐BENZIMIDAZOLES

The Oxidation of Organic Compounds by Active Manganese Dioxide

“…5%-15% yield) and a trace of benzil (474) separated on a fiuorisil column with 3:2 (v /v) chloroform/hexane. Formation of the coupling products (472) and (473) can be explained by invoking a freeradical intermediate. Thus, little formation of benzil has been observed following treatment of deoxybenzoin with manganese dioxide, and, in contrast, no coupling product has been reported from a similar oxidation of diferrocenylmethane.…”

“…In a new example. 318 treatment of deoxybenzoin (471) with manganese dioxide in refiuxing chloroform (or methylcyclohexane) for 3 h gave dibenzoyldiphenylethane (472) in 60% yield. m.p.…”

Synthesis of indolo-quinonediimine derivatives by the thermolysis of 5-(1-benzotriazolyl)-substituted spiro[2H-benzimidazole-2,1′-cyclohexane]

“…The 2,3-dihydrobenzimidazole-2-spirocyclohexane (2), obtained by reaction of 1,2-diaminobenzene 1 with cyclohexanone, both in hot water and dioxane as solvent, 2 when oxidised by manganese dioxide gives the highly stable spiro[2H-benzimidazole-2, 1'-cyclohexane] (3), an isobenzimidazole. 3,4 This stable quinonediimine system undergoes a nucleophilic substitution with benzotriazole, followed by manganese dioxide oxidation, to give compound 4 by Michael-type addition. 5.6 The benzotriazole attacks the unsubstituted isobenzimidazole 3 at C(5) to generate the product 4 in the presence of both Hünig's base and MnO 2 .…”

“…for C 18 H 17 N 5 (303.37): C 71.27; H 5.65; N 23.08. Found: C 71.17; H 5.59; N 23.21 % 1,2,3,4,5,2]imidazo[4,5-b]carbazole(7)…”