* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Stage #1: With nano-BF3/SiO2 In acetonitrile for 0.5 h; Cooling with ice Stage #2: With bromine In acetonitrile at 0 - 20℃; for 5 h;
General procedure: A solution of substituted aniline (2 mmol) in acetonitrile (15 ml) was added to a solution of KSCN (8 mmol) in acetonitrile (15 ml). Then, 0.06 g (30 mol percent BF3) of nano-BF3/SiO2 was added to the mixture, then was placed in a freezing mixture of ice and salt and mechanically stirred for 30 min. Then, bromine (4 mmol, 0.2 ml) in acetonitrile (3 ml) as solvent was added from a dropping funnel at such a rate that the temperature never rose beyond 0°C. After all the bromine was added at 60 min, the solution was stirred for 4 h at room temperature. The progress of the reaction was monitored by TLC. Then, the mixture was poured into water with stirring and the mixture was heated to 70°C on a steam bath and filtered hot to remove the catalyst and the recovered catalyst was washed with acetone and reused in the reaction. The filtrate was neutralized with 10 percent NaOH solution and the precipitate was collected on a filter, dried and recrystallized from ethanol (10 ml) to afford the corresponding products. All of the 2-aminobenzothiazole products were identified by physical and spectroscopic data as reported below, compared and contrasted with authentic samples.#10;Spectral data for selected products#10;6-Bromo-1,3-benzothiazol-2-amine (2e) Yellow solid; Yield = 93 percent; m.p. =202–204°C; (m.p. = 203°C), FT-IR (KBr)/t(cm-1): 3315, 3012, 2835,1580, 1476, 1261, 920, 742, 512. 1H NMR (400 MHz, CDCl3)/d ppm: 5.44 (s, 2H, NH2) 7.4–7.5 (d, 2H, Ar–H), 7.71 (s, 1H, Ar–H); 13C NMR/(100 MHz, DMSO-d6)/d ppm: 119, 120.9, 125.15, 126.07, 133.1, 152.15, 167.75.#10;
Reference：
[1] Synlett, 2012, vol. 23, # 15, p. 2219 - 2222
[2] Research on Chemical Intermediates, 2016, vol. 42, # 12, p. 7855 - 7868
2
[ 1147550-11-5 ]
[ 88-74-4 ]
[ 6973-51-9 ]
Yield
Reaction Conditions
Operation in experiment
41%
Stage #1: at 10℃; for 0.5 h; Cooling with ice Stage #2: at 0 - 20℃;
General procedure: GP2-1: In a flask were added by ammoniumthiocyanate (2.2 eq) and HOAc (5 volume), bromine (1.1 eq) in HOAc (5 volume)was added dropwise under ice-cooled condition, which was stirred at 10 0Cfor 30 min. After filtering off the solid, the filtrate was collected.In aseparate flask, aniline (1.0 eq) and HOAc (5 volume) were added. Then thefiltrate prepared above was added dropwise under 0 0C within 5 min.The mixture was kept stirring at rt overnight. After removal of solvent underreduced pressure, the residue was diluted with EA, neutralized with saturatedNa2CO3 solution, separated, passed through a pad ofCelite, and concentrated to dryness. The crude was purified by silica gelcolumn.GP2-2: To a round-bottomed flaskwas added 2-aminobenzothiazole (1.0eq) and CuCl2 (1.2 eq) in acetonitrile (10 volume), followed by slowaddition of tert-butyl nitrite (1.2eq). The gas evolved immediately. The reaction was greatly exothermic, and, ifnecessary, ice-water cooling was applied. The mixture was then stirred at rtfor hours, which was monitored by TLC. After completion, the reaction wasquenched by 1M HCl, washed by 1 M HCl twice and extracted by EA. The combinedorganic layer was washed by brine, dried over Na2SO4, concentrated and purifiedby flash column to give the product.
Reference：
[1] Medicinal Chemistry Research, 2011, vol. 20, # 7, p. 1033 - 1041
[2] Bioorganic and Medicinal Chemistry, 2015, vol. 23, # 24, p. 7661 - 7670
[3] Journal of Enzyme Inhibition and Medicinal Chemistry, 2011, vol. 26, # 4, p. 527 - 534
3
[ 51039-84-0 ]
[ 6973-51-9 ]
Reference：
[1] Journal of the Chemical Society, 1927, p. 1190
[2] Helvetica Chimica Acta, 1940, vol. 23, p. 328,330
[3] Journal fuer Praktische Chemie (Leipzig), 1974, vol. 316, p. 154 - 158
[4] Acta Crystallographica Section C: Crystal Structure Communications, 1996, vol. 52, # 4, p. 1040 - 1042
4
[ 2942-08-7 ]
[ 6973-51-9 ]
Reference：
[1] J. Gen. Chem. USSR (Engl. Transl.), 1960, vol. 30, p. 1394 - 1397[2] Zhurnal Obshchei Khimii, 1960, vol. 30, p. 1363 - 1366
5
[ 88-74-4 ]
[ 6973-51-9 ]
Reference：
[1] Chemistry of Heterocyclic Compounds, 2009, vol. 45, # 11, p. 1343 - 1353
[2] European Journal of Medicinal Chemistry, 2010, vol. 45, # 9, p. 4293 - 4299
[3] Archiv der Pharmazie, 2010, vol. 343, # 11-12, p. 692 - 699
6
[ 1280582-63-9 ]
[ 6973-51-9 ]
Reference：
[1] Letters in Drug Design and Discovery, 2011, vol. 8, # 9, p. 717 - 724
[2] Letters in Drug Design and Discovery, 2011, vol. 8, # 8, p. 717 - 724
7
[ 88-74-4 ]
[ 6973-51-9 ]
Reference：
[1] Letters in Drug Design and Discovery, 2011, vol. 8, # 9, p. 717 - 724
[2] Letters in Drug Design and Discovery, 2011, vol. 8, # 8, p. 717 - 724
8
[ 95-16-9 ]
[ 6973-51-9 ]
Reference：
[1] J. Gen. Chem. USSR (Engl. Transl.), 1960, vol. 30, p. 1394 - 1397[2] Zhurnal Obshchei Khimii, 1960, vol. 30, p. 1363 - 1366
9
[ 149-30-4 ]
[ 6973-51-9 ]
Reference：
[1] J. Gen. Chem. USSR (Engl. Transl.), 1960, vol. 30, p. 1394 - 1397[2] Zhurnal Obshchei Khimii, 1960, vol. 30, p. 1363 - 1366
General procedure: GP2-1: In a flask were added by ammonium thiocyanate (2.2 eq) and HOAc (5 volume), bromine (1.1 eq) in HOAc (5 volume) was added dropwise under ice-cooled condition, which was stirred at 10 C. for 30 min. After filtering off the solid, the filtrate was collected. (0084) In a separate flask, aniline (1.0 eq) and HOAc (5 volume) were added. Then the filtrate prepared above was added dropwise under 0 C. within 5 min. The mixture was kept stirring at rt overnight. After removal of solvent under reduced pressure, the residue was diluted with EA, neutralized with saturated Na2CO3 solution, separated, passed through a pad of Celite, and concentrated to dryness. The crude was purified by silica gel column. 2-amino-5,6,7-trimethoxybenzothiazole The title compound was prepared according to GP2-1, and the crude was chromatographed (PE/EA=5/1 to 1/1 as eluent) to get grey solid. (690 mg, 18% yield) LC-MS (ESI): [M+1]+=241.01, tR=3.22 min. 1H NMR (400 MHz, d6-DMSO) delta 7.35 (s, 2H), 6.79 (s, 1H), 3.88 (s, 3H), 3.79 (s, 3H), 3.71 (s, 3H). 13C NMR (101 MHz, d6-DMSO) delta 166.42, 159.82, 152.58, 148.96, 146.11, 135.88, 113.91, 97.97, 71.77, 60.80, 59.87, 55.99.
16
[ 6973-51-9 ]
[ 86-92-0 ]
(5-methyl-2-<i>p</i>-tolyl-2,4-dihydro-pyrazol-3-ylidene)-(4-nitro-benzothiazol-2-yl)-amine[ No CAS ]
General procedure: GP2-1: In a flask were added by ammoniumthiocyanate (2.2 eq) and HOAc (5 volume), bromine (1.1 eq) in HOAc (5 volume)was added dropwise under ice-cooled condition, which was stirred at 10 0Cfor 30 min. After filtering off the solid, the filtrate was collected.In aseparate flask, aniline (1.0 eq) and HOAc (5 volume) were added. Then thefiltrate prepared above was added dropwise under 0 0C within 5 min.The mixture was kept stirring at rt overnight. After removal of solvent underreduced pressure, the residue was diluted with EA, neutralized with saturatedNa2CO3 solution, separated, passed through a pad ofCelite, and concentrated to dryness. The crude was purified by silica gelcolumn.GP2-2: To a round-bottomed flaskwas added 2-aminobenzothiazole (1.0eq) and CuCl2 (1.2 eq) in acetonitrile (10 volume), followed by slowaddition of tert-butyl nitrite (1.2eq). The gas evolved immediately. The reaction was greatly exothermic, and, ifnecessary, ice-water cooling was applied. The mixture was then stirred at rtfor hours, which was monitored by TLC. After completion, the reaction wasquenched by 1M HCl, washed by 1 M HCl twice and extracted by EA. The combinedorganic layer was washed by brine, dried over Na2SO4, concentrated and purifiedby flash column to give the product.
General procedure: A solution of substituted aniline (2 mmol) in acetonitrile (15 ml) was added to a solution of KSCN (8 mmol) in acetonitrile (15 ml). Then, 0.06 g (30 mol % BF3) of nano-BF3/SiO2 was added to the mixture, then was placed in a freezing mixture of ice and salt and mechanically stirred for 30 min. Then, bromine (4 mmol, 0.2 ml) in acetonitrile (3 ml) as solvent was added from a dropping funnel at such a rate that the temperature never rose beyond 0C. After all the bromine was added at 60 min, the solution was stirred for 4 h at room temperature. The progress of the reaction was monitored by TLC. Then, the mixture was poured into water with stirring and the mixture was heated to 70C on a steam bath and filtered hot to remove the catalyst and the recovered catalyst was washed with acetone and reused in the reaction. The filtrate was neutralized with 10 % NaOH solution and the precipitate was collected on a filter, dried and recrystallized from ethanol (10 ml) to afford the corresponding products. All of the 2-aminobenzothiazole products were identified by physical and spectroscopic data as reported below, compared and contrasted with authentic samples. Spectral data for selected products 6-Bromo-1,3-benzothiazol-2-amine (2e) Yellow solid; Yield = 93 %; m.p. =202-204C; (m.p. = 203C), FT-IR (KBr)/t(cm-1): 3315, 3012, 2835,1580, 1476, 1261, 920, 742, 512. 1H NMR (400 MHz, CDCl3)/d ppm: 5.44 (s, 2H, NH2) 7.4-7.5 (d, 2H, Ar-H), 7.71 (s, 1H, Ar-H); 13C NMR/(100 MHz, DMSO-d6)/d ppm: 119, 120.9, 125.15, 126.07, 133.1, 152.15, 167.75.
With tert.-butylnitrite; copper dichloride; In acetonitrile; at 20℃;
General procedure: GP2-1: In a flask were added by ammoniumthiocyanate (2.2 eq) and HOAc (5 volume), bromine (1.1 eq) in HOAc (5 volume)was added dropwise under ice-cooled condition, which was stirred at 10 0Cfor 30 min. After filtering off the solid, the filtrate was collected.In aseparate flask, aniline (1.0 eq) and HOAc (5 volume) were added. Then thefiltrate prepared above was added dropwise under 0 0C within 5 min.The mixture was kept stirring at rt overnight. After removal of solvent underreduced pressure, the residue was diluted with EA, neutralized with saturatedNa2CO3 solution, separated, passed through a pad ofCelite, and concentrated to dryness. The crude was purified by silica gelcolumn.GP2-2: To a round-bottomed flaskwas added 2-aminobenzothiazole (1.0eq) and CuCl2 (1.2 eq) in acetonitrile (10 volume), followed by slowaddition of tert-butyl nitrite (1.2eq). The gas evolved immediately. The reaction was greatly exothermic, and, ifnecessary, ice-water cooling was applied. The mixture was then stirred at rtfor hours, which was monitored by TLC. After completion, the reaction wasquenched by 1M HCl, washed by 1 M HCl twice and extracted by EA. The combinedorganic layer was washed by brine, dried over Na2SO4, concentrated and purifiedby flash column to give the product.
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