Polycyclic imidazo[1,2-a]pyridine analogs – synthesis via oxidative intramolecular C–H amination and optical properties

Abstract

Oxidative C–H amination has proved to be an efficient strategy to construct pyrido[2′,1′:2,3]imidazo[4,5-b]indoles and their π-expanded analogs.

Regioselective synthesis of nitrosoimidazoheterocycles using tert-butyl nitrite

“…The amino derivatives are key building blocks for the synthesis of polyfused heterocycles. 13 A few control experiments were carried out to understand the reaction pathway. The reaction did not proceed at all in the presence of the radical scavenger TEMPO (3 equiv.…”

“…Chemical shifts are expressed in parts per million (δ) and are referenced to tetramethylsilane (TMS) as the internal standard and the signals were reported as s (singlet), d (doublet), t (triplet), and m (multiplet) and coupling constants J were given in Hz. 13 C NMR spectra were recorded at 100 MHz. HRMS analysis was performed on a Q-TOF mass analyzer using the ESI ionization method.…”

“…9 Green solid, (98%, 45 mg), mp 164-165 °C (lit. mp 165 °C); 1 H NMR (400 MHz, CDCl 3 ): δ 9.77 (d,J = 8.0 Hz,1H),2H),2H),3H),.09 (m, 1H); 13 C NMR (100 MHz, CDCl 3 ): δ 159. 8, 153.2, 145.6, 136.1, 131.5, 131.5, 130.7, 128.8, 126.4, 119.5, 117.4. 7-Methyl-3-nitroso-2-phenylimidazo[1,2-a]pyridine (2b).…”

Synthesis of π‐Expanded Azole‐Fused Imidazo[1,2‐a]pyridine Derivatives and their Photophysical Properties

“…Kim et al prepared indolizino[3,2‐ c ]quinolines via Fe(III)‐catalysed oxidative Pictet–Spengler cyclization approach and evaluated their optical and live cell imaging properties (Scheme c) . The Gryko group prepared 5 H ‐pyrido[2',1':2,3]imidazo[4,5‐ b ]indoles via oxidative intramolecular C–H amination and measured their optical properties (Scheme d) . It has been observed that fusion with an indole scaffold results in the bathochromic shift of absorption and emission maxima.…”

Synthesis of 5-Aryl-5H-pyrido[2',1':2,3]imidazo[4,5-b]indoles by Domino Pd- and Cu-Catalyzed C–N Coupling Reactions

“…25 In order to avoid the employment of isocyanides, the Gryko group reported a four step pathway to prepare PIDI derivatives in moderate yields. 26 The key step in this synthesis was based on Cu-catalyzed C-H amination in the presence of PIDA as oxidant. Our group has developed…”