Atiur Ahmed

KOtBu mediated efficient approach for the synthesis of fused heterocycles via intramolecular O-/N-arylations

A novel and efficient methodology for the synthesis of 6H-benzo[c]chromenes, 6H-benzo[c]chromen-6-ones, carbazoles, dibenzofurans, dibenzooxepins has been developed. The reaction goes through intramolecular O-/N-arylations with sp2C–Br bonds via typical SNAr pathway in presence of potassium-tert-butoxide base.

Pd-free Sonogashira coupling: one pot synthesis of phthalide via domino Sonogashira coupling and 5-exo-dig cyclization

Phthalides have been synthesized exclusively in one pot via Pd-free Sonogashira coupling. A Cu-catalyzed domino Sonogashira coupling and 5-exo-dig cyclization between suitable substituted ortho-bromobenzoic acids and terminal alkynes afforded phthalides in good yields under mild reaction conditions.

One-pot synthesis of highly fluorescent polycyclic benzimidazole derivatives

An efficient one pot synthesis of polycyclic benzimidazole derivatives has been developed (up to 90% yield). The protocol is very mild, metal-free, and not restricted to anhydrous conditions. It also demonstrates an example of preferential electrocyclic reaction over Michael reaction. These new benzimidazole derivatives are highly fluorescent and show a dramatic change with pH; The characteristic bright bluish fluorescence was observed in MeOH (UV-light, 366 nm) but the intensity was totally diminished at pH = 2.5.

Synthesis of α, β and γ-carbolines via Pd-mediated Csp2-H/N–H activation

An efficient method for the synthesis of halo-carbolines has been developed via Pd-catalysed formation of C–N bonds through Csp2-H/N–H activation of 4-methyl-N-[2-(pyridine-3-yl)phenyl] benzenesulfonamide derivatives. Pd(OAc)2 in the presence of Cu(OAc)2 as oxidant afforded halo-carbolines in good to excellent yields with tolerance to a variety of substituents.

Palladium catalyzed one-pot synthesis of 2-(pyridin-4-yl) quinolines via a multicomponent unprecedented reaction of pyridine-4-carbaldehyde, 2-iodoaniline and triethylamine

Palladium catalyzed synthesis of 2-(pyridin-4-yl) quinolines with an unprecedented participation of Et3N in moderate to high yields was achieved in a novel multicomponent one-pot cyclization reaction of readily available pyridine-4-carbaldehyde, 2-iodoaniline and triethylamine in refluxing toluene.