Structure-function Studies of GABA (A) Receptors and Related computer-aided Studies

Multicomponent Cross-Dehydrogenative Coupling of Imidazo[1,2-a]pyridine: Access to Abnormal Mannich and Mannich-Type Reaction

“…Melting points for new solid compounds were recorded on a "TEMPSTAR KPM-207" melting point apparatus and are reported as uncorrected. 1 H and 13 C NMR spectra were recorded on a Bruker Advance III HD (400 MHz for 1 H and 100 MHz for 13 C) spectrometer at room temperature. Chemical shifts were recorded in parts per million (ppm, δ).…”

“…The residual deuterated solvent was used as an internal standard unless stated otherwise (CDCl 3 : δ H = 7.26 ppm; δ C = 77.16 ppm). 1 H and 13 C { 1 H} NMR splitting patterns are designated as singlet (s), doublet (d), triplet (t), quartet (q), doublet of doublet (dd), doublet of triplet (dt), and multiplet (m). Coupling constants (J) are reported in hertz (Hz).…”

“…. 33 According to the general procedure, compound 4ab was prepared; TLC (R f ): (PE/EA = 60:40) 0.35; purification by column chromatography on silica gel (petroleum ether/EtOAc gradient = 75:25) afforded 4ab as a white solid (57 mg, 58%); mp (°C): 201−202; HRMS (ESI) m/z: [M + H] + calcd for C 22 H 22 N 3 328.1809; found = 328.1808; 1 H NMR (400 MHz, CDCl 3 ): δ 7.82 (d, J = 7.2 Hz, 1H), 7.75 (d, J = 6.8 Hz, 1H), 7.68 (d, J = 9.2 Hz, 1H), 7.43 (t, J = 7.4 Hz, 2H), 7.34 (t, J = 7.4 Hz, 1H), 7.17 (ddd, J = 9.1, 6.7, 1.1 Hz, 1H), 6.91 (d, J = 8.4 Hz, 1H), 6.85 (s, 1H), 6.69 (td, J = 6.8, 0.8 Hz, 1H), 6.54 (d, J = 8.4 Hz, 1H), 4.39 (s, 2H), 2.87 (s, 3H), 2.07 (s, 3H); 13…”

“…. 23,24 According to the general procedure, compound 4af was prepared; TLC (R f ): (PE/EA = 60:40) 0.36; purification by column chromatography on silica gel (petroleum ether/EtOAc gradient = 70:30) afforded 4af as a brown oil (51 mg, 49%); HRMS (ESI) m/z: [M + H] + calcd for C 22 H 22 N 3 O 344.1758; found 344.1767; 1 H NMR (400 MHz, CDCl 3 ) δ 8.19 (d, J = 6.8 Hz, 1H), 7.77 (d, J = 7.2 Hz, 2H), 7.67 (d, J = 9.2 Hz, 1H), 7.46 (t, J = 7.4 Hz, 2H), 7.37 (t, J = 7.2 Hz, 1H), 7.22 (ddd, J = 8.9, 6.9, 1.1 Hz, 1H), 6.96 (dt, J = 9.9, 2.8 Hz, 2H), 6.86 (dt, J = 9.9, 2.8 Hz, 2H), 6.79 (td, J = 6.8, 0.8 Hz, 1H), 4.68 (s, 2H), 3.78 (s, 3H), 2.66 (s, 3H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 153.7, 145.5, 145.25, 145.17, 134.4, 128.9, 128.6, 128.0, 125.0, 124.8, 117.9, 117.5, 116.7, 114.8, 112.4, 55.8, 48.1, 38.5.…”

“…The resulting crude product without workup was directly taken up for the silica gel column using petroleum ether and ethyl acetate (50:50) to afford the desired product 7 as a brick red powder (98% yield, 0.46 mg). TLC (R f ): (PE/EA = 30:70) 0.44; mp (°C): 127−128; HRMS (ESI) m/z: [M + H] + calcd for C 31 H 24 N 3 O 2 470.1864; found 470.1870; 1 H NMR (400 MHz, CDCl 3 ): δ 8.04 (dd, J = 7.6, 0.8 Hz, 1H), 7.87 (dd, J = 7.6, 0.8 Hz, 1H), 7.79 (d, J = 7.2 Hz, 2H), 7.75 (d, J = 6.8 Hz, 1H), 7.72−7.66 (m, 2H), 7.59 (td, J = 7.6, 1.2 Hz, 1H), 7.45 (t, J = 7.4 Hz, 2H), 7.37 (t, J = 7.4 Hz, 1H), 7.21 (ddd, J = 8.9, 6.9, 1.1 Hz, 1H), 7.13 (d, J = 8.4 Hz, 2H), 7.04 (d, J = 8.4 Hz, 2H), 6.78 (td, J = 6.8, 0.8 Hz, 1H), 6.10 (s, 1H), 4.51 (s, 2H), 3.37 (s, 3H); 13…”