... The organic layer was washed with 10 mL each of 1 N HCl, HzO, saturated NaHC03 solution, and brine then dried with MgSO,, filtered, and concentrated to give 129 mg of crude product as an oily solid. ... Page 2. N-Protected Amino Acid Active Esters J. Org. Chem., Vol. 52, No. ...