Synthesis of Methyl 3-Azidothieno[2,3-b]pyridine-2-carboxylates and Application of the Huisgen Reaction

Abstract

The preparation of new substituted methyl 3-azidothieno[2,3-b]pyridine carboxylates by azotization of methyl 3-aminothieno[2,3-b]pyridine and subsequent treatment with sodium azide is described. Via Huisgen’s 1,3-dipolar cycloaddition between substituted alkynes and the prepared azides, methyl 1,2,3-triazolo-thieno[2,3-b]pyridine carboxylates have been obtained.

Design, Synthesis, and Screening of Pyridothieno[3,2-b]indole and Pyridothieno[3,2-c]cinnoline Derivatives as Potential Biologically Active Molecules

“…13 C NMR (100 MHz, DMSO-d6): δ = 161.9 (C-8a), 159.4 (C=O), 154.6 (C-7), 145.0 (C-2), 143.9 (C-9b), 139.9 (C-5), 136.6 (C-4a), 130.3 (C-3a), 121.2 (C-6), 120.0 (C-4b), 107.3 (C-3), 99.7 (C-9a), 52.2 (COOCH3), 24.0 (7-CH3), 20.0 (5-CH3). (20), 300 [M] + (100), 269 (6), 257 (11), 242 (8).…”

“…Yield: 0.75 g (85%); orange solid; mp 322-323⁰C (DMSO). IR: 3599 cm -1 (NH (18), 251 (91), 250 (30), 249 (11), 239 (11), 235 (12), 224 (18), 211 (11), 209 (18), 178 (10), 164 (20), 139 (11), 119 (11), 101 (16), 98 (12), 91 (25), 77 (12), 76 (15), 75 (13), 69 (30), 65 (10), 63 (34), 51 (24), 45 (20), 43 (57), 42 (27), 41 (23). Anal.…”

“…So, 3-azidothieno[2,3-b]pyridines are used in AAC reactions to produce corresponding 1,2,3-triazoles. 11 1,2,3-Triazole formation is postulated as an intermediate stage in the interaction between ethyl 3-azidothieno[2,3-b]pyridine-2-carboxylate with acetonitriles to form pyrido[3′,2′:4,5]thieno[2,3e][1,2,3]triazolo[1, 5-a]pyrimidines. 12 On the other hand, azide group is a well-known precursor for nitrenes whose insertion in C-H bonds allows the preparation of azaheterocycles.…”