Pd(PPh3)4 (32 mg, 0.03 mmol), (R)-4-[2-(6-bromo-2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-2-methyl-piperazine-1-carboxylic acid tert-butyl ester (246 mg, 0.56 mmol) and 2-isopropenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (113 mg, 0.67 mmol) were dissolved in DMF (1.87 mL). Cs2CO3 (549 mg, 1.7 mmol) dissolved in water (0.37 mL) was added to the DMF solution. The reaction was degassed and heated to 85° C. for 18 h then was filtered and concentrated. Column chromatography on silica gel (gradient elution, 0-100% EtOAc/petrol), gave (R)-4-[2-(6-isopropenyl-2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-2-methyl-piperazine-1-carboxylic acid tert-butyl ester (0.18 g) as a yellow oil. 10% Pd/C (48 mg, 0.05 mmol) and (R)-4-[2-(6-isopropenyl-2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-2-methyl-piperazine-1-carboxylic acid tert-butyl ester (0.18 g) were mixed with MeOH (4.5 mL). The reaction was hydrogenated at 1 bar for 30 min at ambient temperature then filtered under vacuum and concentrated, to give the title compound (157 mg, 86%) as a colourless oil. 1H NMR (Me-d3-OD): 8.08 (1H, s), 7.15 (1H, d), 6.95 (1H, d), 4.35-4.18 (3H, m), 3.83 (1H, d), 3.30 (2H, s), 3.25-3.12 (3H, m), 2.97-2.76 (3H, m), 2.33 (1H, dd), 2.20-2.08 (1H, m), 1.48 (9H, s), 1.31 (3H, d), 1.25 (6H, d).
