Triphenylphosphine → Formate

Participants

Reaction Steps

To a solution of 2-ethyl-4-(5-{3-[(ethyl-methyl-amino)-methyl]-5-methyl-phenyl}-[1,2,4]oxadiazol-3-yl)-6-methyl-phenol (100 mg, 273 μmol) in THF (2 mL), PPh3 (107 mg, 409 μmol) followed by 2,2-dimethyl-[1,3]dioxan-5-ol (54 mg, 409 μmol) was added. The mixture was stirred at 0° C. for 10 min before DEAD (178 mg, 409 μmol, 188 μL of a 40% solution in toluene) was added. Stirring was continued at rt for 16 h. Another portion of PPh3 (107 mg, 409 μmol) and DEAD (178 mg, 409 μmol) was added and the mixture was stirred at rt for another hour. The solvent was removed in vacuo and the residue was dissolved in MeCN and separated by prep. HPLC. The acetal intermediate containing fractions were combined and concentrated. The residue was dissolved in MeCN (0.5 mL) and 1N aq. HCl (0.4 mL) and allowed to stand at rt for 10 min before it was again purified by prep. HPLC to give the title compound as a formate salt in the form of a white lyophilisate (71 mg). LC-MS: tR=0.55 min; [M+1]+=440.22; 1H NMR (D6-DMSO): δ 1.06 (t, J=7.0 Hz, 3H), 1.21 (t, J=7.5 Hz, 3H), 2.15 (s, 3H), 2.37 (s, 3H), 2.42-2.48 (m, 5H), 2.78 (q, J=7.5 Hz, 2H), 3.56 (s, 2H), 3.60 (dd, J=11.5 Hz, 5.3 Hz, 2H), 3.64 (dd, J=11.5, 5.0 Hz, 2H), 3.98 (quint, J=5.3 Hz, 1H), 4.77 (br s, 1H), 7.47 (s, 1H), 7.76-7.79 (m, 2H), 7.90 (s, 1H), 7.93 (s, 1H), 8.18 (s, 1H, formate).

Provenance & Evidence