Gram-scale transamidation procedure

A scintillation vial containing a magnetic stir bar was flame-dried under reduced pressure, and then allowed to cool under N₂. The vial was charged with SI-7 (2.22 mmol, 1.0 equiv) and the free-based amino ester SI-28 (2.66 mmol, 1.2 equiv). The vial was flushed with N₂, then taken into a glove box and charged with Ni(cod)₂ (0.111 mmol, 5 mol%) and SIPr (0.222 mmol, 10 mol%). Subsequently, toluene (2.22 ml, 1.0 M) was added. The vial was sealed with a Teflon-lined screw cap, removed from the glove box and stirred at 35 °C for 14 h. After cooling to 23 °C, the mixture was diluted with hexanes (5.0 ml) and filtered over a plug of silica gel (100 ml of EtOAc eluent). The volatiles were removed under reduced pressure, and the crude residue was purified via flash chromatography (20:1 hexanes:EtOAc→15:1→5:1) to yield amide product 33 (quant. yield).