A solution of (R)-1-(2-chloro-7-methylquinazolin-4-yl)pyrrolidin-3-amine (100 mg, 0.38 mmol) in 2 mL of THF was cooled to −30° C. To it was added Et3N followed by the addition of neopentyl chloroformate (53 μL, 0.38 mmol) dropwise. The reaction was complete after 5 minutes. The reaction was quenched with water, the layers separated, and the aqueous layer was twice extracted with CH2Cl2. The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. Purification via silica gel chromatography using 0%-10% EtOAc in DCM gave (R)-neopentyl 1-(2-chloro-7-methylquinazolin-4-yl)pyrrolidin-3-ylcarbamate (100 mg, 70% yield). LC/MS: m/z 377.5 (M+H)+ at 2.90 min (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)).
