Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)₃ catalyst in the reaction selectivity

• Natividad Herrera Cano,
• Jorge G. Uranga,
• Mónica Nardi,
• Antonio Procopio,
• Daniel A. Wunderlin and
• Ana N. Santiago

Beilstein J. Org. Chem. 2016, 12, 2410–2419, doi:10.3762/bjoc.12.235

• successfully applied to the synthesis of natural products [26][27][28]. For instance, an efficient method for the synthesis of a wide range of 3,3-dimethyl-11-alkyl, or aryl 2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepin-1-ones was reported using erbium(III) trifluoromethanesulfonate, Er(OTf)3 as catalyst

• procedure with short reaction time (2–5 min), affording single products in excellent yields (75–99%). This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds. Keywords: catalysis; charge density; condensation; erbium(III

• ) trifluoromethanesulfonate; green procedure; heterocycle; Introduction The formation of heterocyclic compounds is a very important task in organic synthesis, mainly because they are present in numerous biologically active compounds and in several natural products [1]. Among them the presence of benzimidazole [2][3][4][5][6