Triethylamine → Boc-His(Ts) 3-cyclohexylalaninal

Participants

Reaction Steps

To a mixture of the dipeptide alcohol [18a] (2.0 g, 3.65 mmol), triethylamine (1.30 g, 12.85 mmol, 3.5 eq) and DMSO (6 ml) is added at room temperature SO3 ·pyridine (2.03 g, 12.75 mmol, 3.5 eq) in DMSO (6 ml) and the mixture is stirred for 35 minutes. The reaction mixture is poured on ice, and the resultant aqueous mixture is extracted with ethyl acetate (20 ml×3). The organic layer is subsequently washed with 10% aqueous citric acid, saturated aqueous sodium chloride (×2), 7% aqueous sodium bicarbonate, and saturated aqueous sodium chloride, dried over MgSO4, and concentrated to dryness in vacuo. The resultant residue is purified with silica gel chromatography (SiO2 :100 g, CH2Cl2 :MeOH=95:5) to obtain Boc-His(Ts)-3-cyclohexylalaninal [14a] (1.67 g, 84%) in amorphous powder.

Provenance & Evidence