Hypervalent iodine(iii) catalyzed oxidative C–N bond formation in water: synthesis of benzimidazole-fused heterocycles

Abstract

A diverse array of benzimidazole-fused heterocycles was synthesized by in situ generated hypervalent iodine(iii) catalyzed intramolecular oxidative C–N bond formation in water and under ambient conditions.

Benzimidazopurine nucleosides from N6-aryl adenosine derivatives by PhI(OAc)2-mediated C–N bond formation, no metal needed

“…5–7 Of relevance to the present work are the approaches to synthesis of benzimidazoles and azabenzimidazoles using hypervalent iodine reagents. Examples include cyclizations of appropriate precursors with PhI/CH 3 CO 3 H, 8 PhI(OAc) 2 or PhI(OTFA) 2 , 9–11 PhI(OAc) 2 / m -CPBA/ p -TsOH or Koser’s reagent, 12 and rearrangements of N -benzyl-2-aminopyridines. 13 …”

Pd‐Catalyzed versus Uncatalyzed, PhI(OAc)2‐Mediated Cyclization Reactions of N6‐([1,1′‐Biaryl]‐2‐yl)Adenine Nucleosides

“…Conducting the reaction at room temperature with 20 mol% of Pd(OAc) 2 led to reasonable product formation, but the reaction remained incomplete (entry 9). PhI(OTFA) 2 and [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser’s reagent), which have been used for cyclization reactions of simpler systems, [20,23–25] led only to degradation of substrate 3 . This clearly shows the narrow window of reagent compatibility with these sensitive nucleoside substrates.…”

Polycyclic Benzimidazole: Synthesis and Photophysical Properties

“…The rate of intramolecular cyclization depends on the steric interaction. Alkyl group present ortho to the N‐ aryl group has deleterious effect compare to the para substituents …”

“…Alkyl group present ortho to the N-aryl group has deleterious effect compare to the para substituents. [33] Polycyclic benzimidazole 116 derivatives were synthesized by the solid-state condensation of diamine 11 and aromatic anhydride 115 substituents via direct sublimation method. Their physical properties were also examined (Scheme 22).…”