The Synthesis of 4-Carbalkoxy-5-thioalkyl-1,2,3-thiadiazoles

Thiadiazoles

“…In this way, benzo-1,2,3-thiadiazole 9 has been synthesized in 77% yield by reaction of ortho-aminothiophenol (53) with sodium nitrite in acetic acid (Scheme 14.12) [44]. An alternative way to generate a-diazothiocarbonyl compounds exploits the reaction of species bearing an active methylene group such as compound 54, with azides (Scheme 14.13) [45].…”

Addition of Diazo Compounds ipso-C–H Bond to Carbon Disulfide: Synthesis of 1,2,3-Thiadiazoles under Mild Conditions

“…The products were purified by column chromatography on silica gel (300− 400 mesh, from Qingdao, China). NMR spectra were measured on a Bruker ARX400 ( 1 H at 400 MHz, 13 C at 100 MHz, 19 F at 377 MHz) magnetic resonance spectrometer. The chemical shifts (δ) are reported as ppm using tetramethylsilane as the internal standard (s = singlet, d = doublet, t = triplet, q = quartet, dd = doublet of doublets, dt = doublet of triplets, m = multiplet), and the coupling constants (J) are reported in hertz (Hz).…”

“…Ethyl 5-(Benzylthio)-1,2,3-thiadiazole-4-carboxylate (3a). 13 Yellowish-green solid, yield 78% (110 mg); mp 83−84 °C; R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1− 50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.47−7.30 (m, 5H), 4.51 (q, J = 7.1 Hz, 2H), 4.26 (s, 2H), 1.46 (t, J = 7.1 Hz, 3H); 13 Ethyl 5-((4-Methylbenzyl)thio)-1,2,3-thiadiazole-4-carboxylate (3b). White solid, yield 68% (100 mg); mp 93−94 °C; R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1− 50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.32 (d, J = 8.0 Hz, 2H), 7.17 (d, J = 7.9 Hz, 2H), 4.51 (q, J = 7.1 Hz, 2H), 4.23 (s, 2H), 2.35 (s, 3H), 1.46 (t, J = 7.1 Hz, 3H); 13 Ethyl 5-((2-Methylbenzyl)thio)-1,2,3-thiadiazole-4-carboxylate (3c).…”

“…13 Yellowish-green solid, yield 78% (110 mg); mp 83−84 °C; R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1− 50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.47−7.30 (m, 5H), 4.51 (q, J = 7.1 Hz, 2H), 4.26 (s, 2H), 1.46 (t, J = 7.1 Hz, 3H); 13 Ethyl 5-((4-Methylbenzyl)thio)-1,2,3-thiadiazole-4-carboxylate (3b). White solid, yield 68% (100 mg); mp 93−94 °C; R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1− 50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.32 (d, J = 8.0 Hz, 2H), 7.17 (d, J = 7.9 Hz, 2H), 4.51 (q, J = 7.1 Hz, 2H), 4.23 (s, 2H), 2.35 (s, 3H), 1.46 (t, J = 7.1 Hz, 3H); 13 Ethyl 5-((2-Methylbenzyl)thio)-1,2,3-thiadiazole-4-carboxylate (3c). White solid, yield 59% (87 mg); mp 90−91 °C; R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1− 50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.41−7.15 (m, 4H), 4.50 (q, J = 7.1 Hz, 2H), 4.25 (s, 2H), 2.43 (s, 3H), 1.45 (t, J = 7.1 Hz, 3H); 13 Ethyl 5-((4-Bromobenzyl)thio)-1,2,3-thiadiazole-4-carboxylate (3d).…”

“…4 Ethyl 5-(Allylthio)-1,2,3-thiadiazole-4-carboxylate (3f). Yellow oil, yield 50% (58 mg); R f = 0.25 (petroleum ether:EtOAc = 10:1); petroleum ether:EtOAc = 100:1−50:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 5.90 (m, 1H), 5.50 (dd, J = 17.0, 0.7 Hz, 1H), 5.38 (d, J = 10.1 Hz, 1H), 4.52 (q, J = 7.1 Hz, 2H), 3.71 (d, J = 6.7 H z, 2H), 1.47 (t, J = 7.1 Hz, 3H); 13 1-(5-(Benzylthio)-1,2,3-thiadiazol-4-yl)-4-methylpentan-1-one (3i). Yellow oil, yield 62% (95 mg); R f = 0.20 (petroleum ether:EtOAc = 40:1); petroleum ether:EtOAc = 100:1 as eluent; 1 H NMR (400 MHz, CDCl 3 ) δ 7.48−7.28 (m, 5H), 4.23 (s, 2H), 3.28 (t, J = 7.2 Hz 2H), 1.68 (m, 3H), 0.95 (d, J = 6.4 Hz, 6H); 13 (5-(Benzylthio)-1,2,3-thiadiazol-4-yl)(morpholino)methanone (3j).…”