2,5-DibroMopyridine-3,4-diaMine

To the mixture of X-1 (10.0 g, 10 mmol) dissolved in HBr 48percent (200 mL), BrTo the mixture of X-1 (10.0 g, 10 mmol) dissolved in HBr 48percent (200 mL), Br2 (12.5 mL, 13.4 mmol) was added dropwise under ice-water cooling bath, maintaining the temperature below 40°C. After that, the mixture was heated at 110°C for 5 hrs. The reaction mixture was cooled to rt, filtered and washed with little water. The filter cake is basified to pH 7--8 with saturated aq. NaHCO3 and extracted with EtOAc (200 mLx3). The combined organic layer was washed with brine, dried over anhydrous Na2SO4 and concentrated to yield X-2 (17.2 g, 71percent yield). ‘H NMR (DMSO-d6, 400 MHz) 5 7.95 (s, 1H), 5.20 (brs, 4H).The synthesis of 3, 4-diamino-2, 5-dibromopyridine was improved on the basis of the method reported in a literature [18]. The mixture of pyrido-3, 4-diamine(2 g, 18.3 m mol) with an aqueous HBr (48percent, 30 ml) were prepared in a 250 ml three-neck round bottom flask with a magneton inside. After the mixture was heated to 100 deg.C, bromine(2.5 ml) was added dropwise, and the solution was stirred for 5 h at 135 deg.C. After the mixture was cooled to room temperature, an aqueous solution of Na2S2O3, an aqueous solution of Na2CO3, and distilled water were added in this order to get a yellow precipitate. Then the precipitate was separated by filtration and washed with distilled water three times. Recrystallization from the mixture solution of toluene: THF (v:v = 5:1) gave white flocculence solid, yielded: 50percent. 1H NMR (DMSO, 400 MHz, ppm): d=7.53 (s, 1H), 5.99 (s, 2H), 5.03 (s, 2H). 13C NMR (DMSO, 101 MHz, ppm): d = 139.93, 139.13, 129.54, 126.67, 106.22 (seeFig. S1 in Supporting Informations)The mixture of 3, 4-diaminopyridine (5.45 g, 50 mmol) with 48percent hydrobromic acid (24 mL) in a 50 mL flask was heated to reflux while stirring. After adding bromine (8 mL, 155.7 mmol) dropwise, the reaction mixture was heated for 16 h at 80 °C then cooled down to the room temperature. The mixture was filtered and washed with a saturated solution of NaIn a three-neck 100 mL round-bottom flask, was added 3, 4-diaminopyridine (1) (5.0 g, 45.2 mmol) with 9.3 mL of 48 percent hydrobromic acid. The resulting mixture was heated to reflux while stirring and bromine (7.6 mL, 148.5 mmol) was added dropwise. The reaction mixture was refluxed for 5 h and cooled to ambient temperature. The mixture was filtered and washed with a saturated solution of Na2S2O3 (100 mL), Na2CO3 (100 mL) and finally water (100 mL). To complete the neutralization process, the crude product was refluxed 30 min in a 10 percent solution of Na2CO3. The mixture was then filtered and washed with water. The brown-dark product wasfirst purified by column chromatography ethyl acetate/hexane(3:2) and by recrystallization from methanol to give compound 2 as an orange powder (3.1 g, 25.5 percent). 1HNMR(Acetone-d6, 300 MHz, δ/ppm): 7.65 (s, 1H), 5.54 (br, 2H), 4.66 (br, 2H). 13C NMR (100 MHz, Acetone-d6, δ/ppm):140.66, 140.45, 129.81, 128.30, 106.24. EI-MS m/z: [M +H]+ Cacld for C5H5Br2N3: 264.88, Found: 264.70.

Molecular Weight:266.92
XLogP3:1.2
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:3
Exact Mass:266.88297
Monoisotopic Mass:264.88502
Topological Polar Surface Area:64.9
Heavy Atom Count:10
Complexity:122
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes