Trifluoroacetic acid → (2R,3R,4S,5R)-2-(6-amino-9H-purin-9-yl)-5-((methyl(3-(2-(5-(oxetan-3-yl)-1H-benzo[d]imidazol-2-yl)ethyl)cyclobutyl)amino)methyl)tetrahydrofuran-3,4-diol

Participants

Reaction Conditions

Reaction Steps

To a cooled (ice bath) flask containing 9-((3aR,4R,6R,6aR)-2,2-dimethyl-6-((methyl(3-(2-(5-(oxetan-3-yl)-1H-benzo[d]imidazol-2-yl)ethyl)cyclobutyl)amino)methyl)tetrahydrofuro[3,4-d][1,3]dioxol-4-yl)-9H-purin-6-amine (0.28 g, 0.42 mmol) was added a precooled (ice bath) solution of trifluoroacetic acid (6.4 mL, 84 mmol) in water (0.75 mL, 42 mmol). The reaction mixture was stirred for 5.75 h at 0° C.; HPLC/LC MS indicated nearly complete consumption of starting material. At 6 h the flask was removed from the cold bath and the volatiles were removed by distillation at rt. The residue was diluted with MeOH (15 mL) and treated with potassium carbonate (0.32 g, 2.3 mmol) and water (1 mL) and the mixture was stirred for 20 min at rt; pH 2. Additional potassium carbonate (0.20 g, 1.4 mmol) was added and the mixture was stirred for 20 min; pH 8-9. The solution was filtered through a fine frit, rinsing with MeOH, and the filtrate was concentrated in vacuo to afford a tan semi-solid. Purification by column chromatography (3×8 cm silica; 10-20% 7 N methanolic NH3/CH2Cl2) afforded the title compound (123 mg, 55%) as a nearly colorless glass: MS (ESI+) for C27H34N8O4 m/z 535.3 (M+H)+; MS (ESI−) for C27H34N8O4 m/z 533.3 (M−H)−; HPLC purity >95% (ret. time 1.765 min); 1H NMR (400 MHz, d4-MeOH) mixture of cis/trans isomers δH 8.29-8.25 (m, 1H), 8.21-8.17 (m, 1H), 7.51 (s, 1H), 7.47 (d, J=8.3 Hz, 1H), 7.26 (dd, J=1.6, 8.3 Hz, 1H), 6.00-5.96 (m, 1H), 5.11 (dd, J=5.8, 8.3 Hz, 2H), 4.81-4.76 (m, 2H), 4.73-4.68 (m, 1H), 4.40-4.31 (m, 1H), 4.27-4.13 (series of m, 2H), 3.13-3.03 (m, 0.4H), 2.86-2.66 (series of m, 4.6H), 2.30-1.80 (series of m, 8.6H), 1.55-1.40 (m, 1.4H).

Provenance & Evidence