Hydrogen Bromide → HCID 178480832, compound

Participants

Reaction Conditions

Reaction Steps

To a 50 ml round bottom flask containing a stir bar is added 2 (1.21 g, 4.06 mmol), N-bromo succinimide (1.59 g, 8.94 mmol), AIBN (0.066 g, 0.406 mmol) and CCl4 (20 ml). The flask is fitted with a reflux condenser and refluxed for 3 hours or until TLC (30% EtOAc/Hex) shows full conversion. The contents of the flask are directly filtered into a 50 ml round bottom flask to remove the succinimide and the filtrate is concentrated under reduced pressure to yield a pale yellow oil. This oil is dried under high vacuum overnight. A stir bar is added to the flask containing the crude brominated compound and CH3CN (20 ml) and 1-methyl imidazole (0.73 ml, 8.94 mmol) are added. The flask is fitted with a reflux condenser and heated at 80° C. for 2 hours. After cooling to room temperature, the reaction mixture is transferred to a 100 ml round bottom flask and concentrated under reduced pressure to yield a brown oil. This oil is dried under high vacuum yielding the crude imidazolium bromide as a tan foam. To the flask containing the crude imidazolium bromide is added a stir bar and the foam is dissolved in 40 ml of a 1:1 THF:H2O mixture. LiOH (1.66 g, 40.6 mmol) is added in one portion and the reaction stirred for three hours at 23° C. After three hours, the reaction mixture is acidified to pH 1 with HBr (conc., 48% w/w) and the THF is removed under reduced pressure. After ˜20 ml of solvent is removed the contents of the flask are filtered to remove any solid and the filtrate is left to crystallize. After ˜24 hours white needle crystals began to fall out of solution. In subsequent reactions the filtrate is seeded with product. The crystals are filtered, washed with water, and dried under high vacuum yielding 4 (1.076 g, 45%) as a white crystalline solid. Analytical data for 4: IR (ATR) 3383, 2972, 1710, 1379, 1284, 1261, 1161, 952 cm−1; 1H NMR (500 MHz, DMSO-d6) δ8.73 (s, 2H), 8.01 (s, 2H), 7.96 (d, J=9.2 Hz, 2H), 7.66 (s, 2H), 7.43 (s, 2H), 7.18 (d, J=8.9 Hz) 5.24 (dd, J=104 Hz), 3.77 (s, 3H); 13C (125 MHz, DMSO-d6) δ 166.6, 142.2, 136.8, 132.5, 131.4, 130.7, 130, 129.8, 123.8, 122.5, 50.2, 35.9; HRMS (CI): Exact mass calcd for C24H24O4N4 [M/2]+, 216.09. Found: 216.1.

Provenance & Evidence