p-Toluenesulfonic acid → 5-(2-Oxohexahydrothieno[3,4-d]imidazol-6-yl)-pentanoic Acid 3-Iodopropyl Ester

Participants

Reaction Steps

A solution of biotin (125 mg, 0.5 mmol), 3-iodo-1-propanol (150 μL, 1.6 mmol) and TsOH (10 mg, 0.05 mmol) in PhMe (50 mL)) was heated under reflux and Ar for 3 d in a Dean-Stark apparatus. After cooling down to ambient temperature, the mixture was filtered and the solvent distilled off under reduced pressure. The residue was dissolved in CH2Cl2 (30 mL) and washed with H2O (5 mL). The organic phase was dried (MgSO4) and concentrated under reduced pressure to yield 4 (75 mg, 36%) as a white solid. FABMS: m/z=413 [M+H]+; 1H-NMR (400 MHz, CDCl3): δ=1.40-1.45 (2H, m), 1.61-1.75 (4H, m), 2.10-2.16 (2H, m), 2.30 (2H, t, 7 Hz), 2.79 (1H, d, 13 Hz), 2.88 (1H, dd, 5 and 13 Hz), 3.15-3.18 (1H, m), 3.22 (2H, t, 7 Hz), 4.13 (2H, t, 6 Hz), 4.42-4.45 (1H, m), 4.61-4.65 (1H, m), 7.22 (1H, d, 8 Hz); 7.72 (1H, d, 8 Hz); 13C-NMR (100 MHz, CDCl3): δ=25.0, 28.4, 28.8, 32.6, 34.2, 40.5, 55.8, 61.8, 63.6, 64.4, 164.5, 173.9.

Provenance & Evidence