Catalyst-free Friedel–Crafts hydroxyalkylation of imidazo[1,2-α]pyridines with ethyl trifluoropyruvate

Ball-Milling-Enabled Zn(OTf)2-Catalyzed Friedel–Crafts Hydroxyalkylation of Imidazo[1,2-a]pyridines and Indoles

“…Purification by column chromatography on silica gel (eluent: EtOAc/hexane, 1:1 v/v); off white solid; 48 mg (52%); mp = 168–170 °C (Lit. mp 164–165 °C); FT-IR v max (neat)/cm –1 : 3741,3070, 2360, 1805, 1728, 1280, 1026, 740, 702; 1 H NMR (400 MHz, CDCl 3 ) δ 8.80 (d, J = 7.1 Hz, 1H), 7.64 (d, J = 9.0 Hz, 1H), 7.39 (s, 3H), 7.34 (t, J = 7.5 Hz, 1H), 6.87 (t, J = 6.9 Hz, 1H), 3.61–3.52 (m, 1H), 3.19–3.09 (m, 1H), 0.90 (t, J = 7.1 Hz, 3H); 13 C­{ 1 H} NMR (100 MHz, CDCl 3 ) δ 166. 3, 145.5, 144.9, 133.0, 130.1, 128.8, 127.8, 127.9 (q, J C–F = 282 Hz), 116.7, 113.1, 113.0, 76.5 (q, J C–F = 28 Hz), 63.4, 13.2; HRMS (ESI) m / z : [M + H] + Calcd for C 18 H 16 F 3 N 2 O 3 365.1108; Found 365.1102.…”

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

“…Despite many successful strategies in this field, the regioselective C–H functionalization is still challenging for chemists to combine a C(sp 3 ) carbon of incoming functionalities and C(sp 2 ) carbon of the IP core. The direct C-3 alkylation of imidazopyridines using active malonates and related moieties has been achieved by different routes [ 17 – 20 ]. However, these reactions rely either on harsh reaction conditions or require the preactivation of substrates, which limits their synthetic efficiency.…”

Regioselective C3–H Alkylation of Imidazopyridines with Donor–Acceptor Cyclopropanes

“…Despite these advances, selective alkylation of imidazo­[1,2- a ]­pyridines with donor–acceptor cyclopropanes has not been reported. (Scheme a–c). − Herein, we report the nucleophilic ring-opening reaction of DA-cyclopropanes with imidazo­[1,2- a ]­pyridines (Scheme d). We also investigated three component 1,3-bisfunctionalizations of DA-cyclopropanes.…”