A solution of 29 (115 mg, 0.24 mmol) in DCM (6 mL) was cooled to 0° C. and treated with (R)-(+)-α-methylbenzylamine (36 μL, 0.28 mmol), EDC (71 mg, 0.37 mmol), and HOBT (51 mg, 0.37 mmol). To this solution was then added DIPEA (0.2 mL, 1.2 mmol). The reaction mixture was allowed to warm to ambient temperature. After 16 h, the solution was diluted with DCM, washed with 1M HCl, dried over anhydrous Na2SO4, filtered and concentrated to give crude 30 as an off-white foam. The crude residue was diluted with ACN/H2O containing 0.1% HOAc and purified by reverse-phase HPLC (2″ Dynamax® C18, 10% ACN/H2O to 100% ACN over 30 min). The product-containing fractions were combined and concentrated, diluted with EtOAc and washed successively with saturated NaHCO3 and brine. The combined aqueous layers were back-extracted with DCM and the combined organic extracts were dried over anhydrous Na2SO4, filtered and concentrated to afford 30 as an off-white foam. Mass spectrum, m/z [577.6] (M+H)+.
