Phosphorus heterocycles from 2‐(2‐aminophenyl)‐1H‐benzimidazole

Abstract

AbstractWe report the syntheses of unsaturated six‐membered heterocycles bearing tri‐, tetra‐, and pentacoordinated phosphorus atoms derived from 2‐(2‐aminophenyl)‐1H‐benzimidazol (1). The presence of three different N–H protons allowed to prepare different compounds by selective substitution. Molecules with two (endo and exocyclic) phosphorus atoms were prepared. The free anilinic proton is the most reactive to substitution reactions, followed by the benzimidazolic, and then the anilinic proton involved in the hydrogen bond. Substitution of the exo‐anilinic proton of 1 by Ph2PCl leads a precursor with a hydrogen bond forming a six‐membered ring, which could be substituted by other groups giving more complex molecules. A pentacoordinated phosphorus compound was obtained after oxidative addition of 3,5‐di‐tert‐butyl‐1,2‐benzoquinone to P(III) heterocycle. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:321–332, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20022