2-Amino-3,5-dibromopyridine

yellow to brown fine crystalline powder

Preparation of 1 -(tert-butoxycarbonyl)-3-methyl-2, 3-dihydro-1 H-pyrrolo[2, 3-b]pyridin-5-ylboronic acid (64)Step i: 5General procedure: A mixture of arene (0.5 mmol), IGeneral procedure: To a - 20°C solution of 2-aminopyridineor 2-amino-4-chloropyridine(1 equiv) in DMF was added N-bromosuccinimide(1.1 or 2.2 equiv.) in two portions. The reaction mixture was stirred for 16 hat room temperature and was then poured withstirring into a 1M solution of NaOH (50 mL). The phases were separated and theaqueous layer was extracted with EtOAc. The combined organic phases were washedwith water (2 x 50 mL) and brine (50 mL), dried over MgSOGeneral procedure: To a mixture of 2-aminopyridine (0.5 mmol, 1 equiv), p-TSA (0.4 mmol, 0.8 equiv), 1-butylpyridinium bromide (1.5 mmol, 3 equiv) in a 50 mL Schlenk tube were added 1, 2-dimethoxyethane (2 mL) under air. Then HTo a solution of 2-aminopyridine (9.40 g, 0.1 mol) in EtOH (100 mL) was added dropwise Br2 (5.8 mL, 0.11 mol) maintaining the temperature below 20 °C. When the addition of bromine was completed, the mixture was stirred for 1 h. After removal of EtOH, the residue was made alkaline with a solution of NaOH (5.0 g, 0.13 mol) in H2O (50 mL) and cooled (10 °C). The solid was collected by filtration, slurry washed with cold H2O (10 mL), and then washed with boiling heptane (3 × 20 mL) to remove the 2-amino-3, 5-dibromoaminopyridine, followed by air-drying to constant weight; yield: 13.15 g (76percent); off-white fine crystals; mp 135–136 °C (Lit.17 mp 132–135 °C); Rf = 0.4 (CHCl3–EtOAc). IR (KBr): 3452, 3292, 3153, 2924, 2852, 1628, 1587, 1550, 1481, 1387, 1088, 999 cm–1.1H NMR (CDCl3): δ = 4.57 (br s, 2 H, NH2), 6.41 (d, J = 8.8 Hz, 1 H, H-3), 7.48 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 1 H, H-4), 8.09 (d, J = 2.4 Hz, 1 H, H-6).13C NMR (CDCl3): δ = 108.3, 110.1, 140.2, 148.7, 157.1.MS (EI, 70 eV): m/z (percent) = 174 (88, [M (81Br)]+), 172 (100, [M (79Br)]+), 147 (46), 145 (49), 92 (97), 65 (67), 64 (60), 50 (49).Anal. Calcd for C5H5BrN2: C, 34.71; H, 2.91; N, 16.19. Found: C, 34.59;H, 3.01; N, 16.10.28.2 g (0.3 moles) of 2-aminopyridine were dissolved in 50 ml of acetic acid. The solution is cooled to below 20° by immersion in an ice bath, and 48 g (15.4 ml, 0.3 moles) of bromine dissolved in 30 ml of acetic acid is added dropwise with vigorous stirring over a period of 1 h. Initially the temperature is maintained below 20°. After half the bromine solution has been added, it is allowed to rise to 50° to delay as long as possible the separation of the hydrobromide of 2-amino-5-bromopyridine. At 50° the hydrobromide usually begins to crystallize when about three-quarters of the bromine has been added. When addition of bromine is completed, the mixture is stirred for 1 h and is then diluted with 75 ml of water to dissolve the hydrobromide. The contents of the flask are transferred to a 500 ml beaker and are neutralized, with stirring and cooling, by the addition of 120 ml of 40percent sodium hydroxide solution. 2-Amino-5-bromopyridine, contaminated with some 2-amino-3, 5-dibromopyridine, was filtered and dried. The 2-amino-3, 5-dibromopyridine is removed from the product by washing with three 500-ml. portions of hot petroleum ether. The yield of 2-amino-5-bromopyridine, is 32-34.7 g (62-67percent). mp 134 °C (literature

Molecular Weight:251.91
XLogP3:1.9
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:2
Exact Mass:251.87207
Monoisotopic Mass:249.87412
Topological Polar Surface Area:38.9
Heavy Atom Count:9
Complexity:99
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes