多聚甲醛 → Carbon dioxide methanol

参与物

反应步骤

A cone shaped thick-walled glass vial was charged with a stir bar, (R)-(+)-3-aminoquinuclidine dihydrochloride (97 mg, 0.48 mmol), ammonium acetate (75 mg, 0.97 mmol), phenylglyoxal monohydrate (73 mg, 0.48 mmol), formaldehyde (37%, aqueous—35 μL, 0.48 mmol) and glacial AcOH (1 mL). The vials were sealed and subjected to microwave radiation for 10 minutes at 120° C. The resultant mixture was dilute with EtOAc (1×20 mL) and basified to pH˜13 with 10% NaOH (aq), extracted with EtOAc (3×20 mL), dried over Na2SO4 (s), filtered, and concentrated by rotary evaporation to an orange solid. The material was subjected to flash chromatography (SiO2—12 grams; gradient elution: 1-8% 3 N NH3/MeOH—CH2Cl2 at 20 mL/min over 30 min) to provide a 5:1 regio-isomeric mixture as determined by 1H NMR signal integration of the 5- and 4-phenyl-imidazol-1-yl compounds as orange-yellow crystals (50 mg, 41%). The mixture was subsequently purified by SFC: Berger Cyano column (6 μm particle size, 21 mm ID×150 cm), 15-30% MeOH/CO2 at 50 mL/min, to give (R)-3-(4-phenyl-imidazol-1-yl)-1-azabicyclo[2.2.2]octane (Example 3) as a white tacky gum (6 mg, 5%). Mass spectrum (ES+): M+1: 254 (100%); 1H NMR (300 MHz, CDCl3) δ 1.53 (m, 1H), 1.68-2.01 (m, 3H), 2.15 (app q, J=3.1 Hz, 1H), 2.74 (m, 1H), 2.82-3.0 (m, 3H), 3.19(dd, J=14.5, 5.2 Hz, 1H), 3.50 (ddd, J=14.5, 7.7, 2.2 Hz, 1H), 4.26 (m, 1H), 7.24 (m, 1H), 7.31 (d, J=1.3 Hz, 1H), 7.37 (m, 2H), 7.64 (d, J=1.3 Hz, 1H), 7.77 (d, J=7 Hz, 2H).

来源与证据