NH4I-catalyzed chalcogen(S/Se)-functionalization of 5-membered N-heteroaryls under metal-free conditions

Unconventional Reactivity with DABCO‐Bis(sulfur dioxide): C–H Bond Sulfenylation of Imidazopyridines

“…3‐[(2‐Methoxyphenyl)thio]‐2‐phenylimidazo[1,2‐ a ]pyridine (4h): Yellow solid (77 mg, 45 %); 1 H NMR (300 MHz, CDCl 3 ): δ = 8.27 (d, J = 6.8 Hz, 1H), 8.19 (d, J = 7.0 Hz, 2H), 7.74 (d, J = 9.0 Hz, 1H), 7.48–7.29 (m, 4H), 7.12 (td, J = 7.7 Hz, 1.3 Hz, 1H), 6.91–6.84 (m, 2H), 6.69 (t, J = 8.0 Hz, 1H), 6.39 (dd, J = 7.7, 1.3 Hz, 1H), 3.94 (s, 3H); 13 C NMR (75 MHz, CDCl 3 ): δ = 156.2, 151.9, 147.4, 133.5, 128.6, 128.5, 127.0, 126.7, 125.6, 124.9, 123.4, 121.7, 117.7, 113.0, 110.9, 105.4, 56.0; MS (ES + ): m/z (%) = 332.8 (100) [M + H] + …”

“…4‐[(2‐Phenylimidazo[1,2‐ a ]pyridin‐3‐yl)thio]aniline (4q): White crystals (65 mg, 40 %); 1 H NMR (300 MHz, CDCl 3 ): δ = 8.34 (d, J = 6.9 Hz, 1H), 8.29–8.23 (m, 2H), 7.70 (d, J = 9.0 Hz, 1H), 7.45 (t, J = 7.2 Hz, 2H), 7.41–7.36 (m, 1H), 7.30 (ddd, J = 9.0, 6.9, 1.3 Hz, 1H), 6.94–6.82 (m, 3H), 6.53 (d, J = 8.5 Hz, 2H), 3.62 (s, 2H); 13 C NMR (75 MHz, CDCl 3 ): δ = 150.5, 146.8, 145.6, 133.6, 128.7, 128.5, 128.5, 126.5, 124.6, 122.3, 117.6, 116.2, 113.0, 108.7; MS (ES + ): m/z (%) = 317.8 (100) [M + H] + …”

“…2‐(4‐Fluorophenyl)‐3‐(phenylthio)imidazo[1,2‐ a ]pyridine (6n): Beige solid (115 mg, 70 %); 1 H NMR (300 MHz, CDCl 3 ): δ = 8.27 (d, J = 6.8 Hz, 1H), 8.23–8.16 (m, 2H), 7.72 (d, J = 9.0 Hz, 1H), 7.34 (t, J = 7.8 Hz, 1H), 7.25–7.18 (m, 2H), 7.17–7.08 (m, 3H), 6.99 (d, J = 7.2 Hz, 2H), 6.88 (t, J = 6.5 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 ): δ = 164.8, 161.5, 150.6, 147.6, 135.1, 130.2 (d, J C‐F = 8.2 Hz), 129.6, 126.9, 126.2, 125.6, 124.6, 117.7, 115.5 (d, J C‐H = 21.5 Hz), 113.2, 106.1; MS (ES + ): m/z (%) = 320.7 (100) [M + H] + …”

Direct Catalytic Functionalization of Indazole Derivatives

“…The desired 3-(phenylselanyl)-1H-indazole product (70 b) was obtained with 32% yield (Scheme 70). [128] Next year, the same group first reported Rose Bengal catalyzed blue light-induced selenylation of unprotected 1H-indazole. The desired C-3 selenylated 1H-indazole (71 b) was obtained in high yield when a mixture of 1H-indazole (71 a) and diphenyl diselenide was irradiated with blue light in presence of 4 mol% of Rose Bengal in CH 3 CN for 6 h at room temperature (Scheme 71).…”

Photoinduced, Direct C(sp2)−H Bond Azo Coupling of Imidazoheteroarenes and Imidazoanilines with Aryl Diazonium Salts Catalyzed by Eosin Y

“…Their structure is present in many pharmaceuticals and also has applications in material sciences . Therefore, it is not surprising that the synthesis and functionalization of imidazoheteroarenes have received considerable attention in different areas of scientific research . Analogously, arylazo compounds are widely used in several areas, including the chemical industry, pharmaceuticals, chemosensors, electronics, and liquid crystals ( 1 a – d , Figure ) .…”