Oxone®-mediated halocyclization/demethylation of 2-alkynylthioanisoles with sodium halides towards 3-halobenzo[b]thiophenes

Iodocyclization of 2‐Methylthiophenylacetylenes to 3‐Iodobenzothiophenes and their coupling Reactions under More Sustainable Conditions

“…IR (film): ν=1474 (m), 1427 (w), 1389 (w), 1242 (w), 1065 (m), 1011 (m), 964 (w), 826 (s), 772 (m), 748 (s), 718 (m) cm −1 ; 1 H NMR (CDCl 3 , 500 MHz): δ=7.81 (d, J =8.0, 1 H), 7.77 (d, J =7.9, 1 H), 7.64–7.57 (m, 2 H), 7.57–7.51 (m, 2 H), 7.46 (t, J =7.5, 1 H), 7.39 (t, J =7.5, 1 H); 13 C NMR (CDCl 3 , 75 MHz): δ=141.8, 140.8, 138.9, 133.6, 131.8, 131.5, 126.4, 125.7, 125.6, 123.3, 122.1, 79.9; GC‐MS (EI, 70 eV): m/z =416 [(M+2) + , 46], 414 (M + , 53), 208 (100), 176 (3), 163 (37), 104 (45); HRMS‐ESI ( m/z ): [(M+H) + ] cald for (C 14 H 9 BrIS) + : 414.8648; found: 414.8675. The spectroscopic data agreed with those reported [8a] …”

“…IR (KBr): ν=1597 (m), 1566 (w), 1443 (s), 1273 (m), 1234 (w), 1165 (m), 1126 (w), 988 (w), 856 (m), 802 (m), 741 (m) cm −1 ; 1 H NMR (CDCl 3 , 500 MHz): δ=7.71 (dd, J =8.7, 4.8, 1 H), 7.68–7.63 (m, 2 H), 7.52 (dd, J =9.6, 2.3, 1 H), 7.50–7.42 (m, 3 H), 7.13 (td, J =8.7, 2.3, 1 H); 13 C NMR (CDCl 3 , 125 MHz): δ=161.7 (d, J =242.5), 144.8, 143.5 (d, J =8.9), 134.4 (d, J =8.9), 129.9, 129.1, 128.6, 123.4 (d, J =8.8), 114.3 (d, J =25.1), 112.1 (d, J =24.6), 74.5; GC‐MS (EI, 70 eV): m/z =354 (100), 226 (45), 183 (39), 113 (31); HRMS‐ESI ( m/z ): [(M+H) + ] cald for (C 14 H 9 FIS) + : 354.9448; found: 354.9429. The spectroscopic data agreed with those reported [8a] …”

Halogenative Annulation Reactions of Alkyne-Tethered N- and O-Containing Arenes: Methods for Accessing Aryl-Fused Halogenated N- and O-Heterocycles

“…A new procedure was published which focused mainly in the synthesis of 3-halobenzothiophenes from 2alkynylthioanisoles. 10 Within this work, an example was illustrated for the synthesis of 3-iodoindole (Scheme 3), showing the procedure's amenability to prepare iodinated Nheterocycles. However, this protocol failed to produce the corresponding benzofuran from 2-alkynylanisole.…”

Visible-light-induced halocyclization of 2-alkynylthioanisoles with simple alkyl halides towards 3-halobenzo[b]thiophenes without an external photocatalyst

“…4 Wu, Kesharwani and Cai independently reported copper, iron or oxone-mediated electrophilic cyclization of 2-alkynylthioanisoles using sodium halide as the source of halogen. 5 Recently, Guo et al described the synthesis of C-3 halogenated benzo[ b ]thiophenes from 2-alkynylthioanisoles and potassium halide employing an assembled electrochemistry continuous-flow system. 6 Despite these important advances, most of the current methods have some limitations, and the development of a simple, practical and green alternative protocol to synthesize this class of compounds is still highly desirable.…”