To a solution of (2E,4S)-4-({[(1,1-dimethylethyl)oxy]carbonyl}amino)-6-methyl-2-heptenoic acid (4.70 g, 18.26 mmol) in DMF (30.0 mL) were added BOP reagent (8.08 g, 18.26 mmol) and DIPEA (6.38 mL, 36.5 mmol). After stirring at RT for 5 min, 2,3-dihydro-1H-indole (2.053 mL, 18.26 mmol) was added and stirring continued overnight. The reaction mixture was diluted with water and extracted with EtOAc. The organic layer was washed with brine, dried over Na2SO4, filtered, concentrated in vacuo and purified by flash column chromatography (0-20% EtOAc/hexanes) to afford the title compound (4.83 g, 74%) as a white solid. LC-MS m/z 359 (M+H)+, 1.18 min (ret time).
