(R)-1-Phenylpropylamine → (R)-(+)-1-Phenylpropyl isocyanate

To a solution of 1(R)-phenylpropylamine (14.33 g, 106 mmol) in Et2O (102 mL) was added a 1.0 M solution of HCl/Et2O (212 mL, 212 mmol). The mixture was stirred for 30 min, then the crude solution was evaporated to dryness on a rotary evaporator. The resulting white hydrochloride salt was suspended in toluene (200 mL), triphosgene was added (11.67 g, 39.3 mmol) and the resulting suspension was stirred at reflux for 3 h at room temperature overnight. The reaction mixture was concentrated and the final volume adjusted to 200 mL with toluene giving a final concentration of 0.53M. The resulting isocyanate solution was used as such. An aliquot (170 mL) was concentrated to give a colorless oil.