2.1.1 General procedure 1 (GP1) for the synthesis of starting materials (2a, 4a, 6a, 7a, 8a, 9a, 11a, 12a, 14a, 15a, 18a, 20a, 21a, 22a, 23a, 28a, 31a, 36a) To a solution of the amine nucleophile (2.5 mmol, 1 eq.) in 5 ml of CH2Cl2 solvent triethylamine was added (0.85 ml, 5.0 mmol, 2 eq.). The reaction mixture was stirred for 5 minutes. Di-tertbutyl decarbonate (2.75 mmol, 1.1 eq., or pivaloyl chloride (0.33 ml, 2.75 mmol, 1.1 eq.) was added in portions to the reaction mixture over a period of 5 minutes and left to stir the resulting solution for overnight at room temperature. After completion of the reaction (monitored by GC or TLC), the mixture was quenched with a 1N HCl and extracted with CH2Cl2 (2 x 5 mL). The combined organic layers were then washed with water (2 x 10 ml), dried over anhydrous MgSO4, concentrated under vacuum and the crude mixture was either directly used or further purified by flash column chromatography. If the HCl salt of the amine nucleophile was employed, 3 eq. of Et3N were used.