Potassium Carbonate → 2-(1-Acetyl-6-fluoro-1H-indol-3-ylmethyl)-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere, a solution of 18 (66 g, 0.15 mol) in anhydrous DMF (350 mL) was charged with (n-Bu)4NCl (41.5 g, 0.15 mol), K2CO3 (20.6 g, 0.15 mol), NaHCO2 (10.2 g, 0.15 mol), and Pd(OAc)2 (3.35 g, 0.015 mol) at ambient temperature. The heterogeneous mixture was immersed in a pre-heated (85° C.) oil bath. After 1 h, TLC analysis revealed some 18 remained therefore more catalyst (1 g) was added. After 1.5 h, another charge of catalyst (0.6 g) was added. After an additional 1.5 h of heating, 18 had been completely consumed by TLC analysis [TLC analysis, 2% MeOH/DCM, Rf(18)=0.7; Rf(19)=0.8]. The warm reaction mixture was transferred to an ice water bath to cool then diluted with diethyl ether and filtered through a pad of celite. The solids were washed with diethyl ether and the filtrate was washed several times with water to remove DMF then once with brine, dried over anhydrous Na2SO4, filtered, and concentrated to afford 52.5 g of crude 19 which was used without further purification. 1H NMR (CDCl3, 300 MHz) δ8.18 (m, 1H), 7.60 (m, 1H), 7.18 (m, 1H), 7.05 (dt, J=2.4, 8.7 Hz, 1H), 4.13 (m, 1H), 3.41 (m, 1H), 3.33 (m, 2H), 3.17 (app dd, J=14.1, 38.1 Hz, 1H), 2.61 (s, 3H), 1.83 (m, 3H), 1.69 (m, 1H), 1.49 (s, 9H) ppm.

Provenance & Evidence