Hydrochloric Acid → 4-(4-Nitro-phenyl)-pyrrolidine-3-carboxylic acid ethyl ester

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Reaction Steps

A stirred solution of 4-(4-nitro-phenyl)-pyrrolidine-1,3-dicarboxylic acid 3-ethyl ester 1-vinyl ester (6 g, Reference Example 5) in dioxane (30 ml), at 25° C., was treated dropwise with hydrochloric acid (15 ml, 4N). After stirring for 2 hours the mixture was treated with a further aliquot of hydrochloric acid (15 ml, 4N) and stirring was continued at 25° C. for a further 2 hours. The reaction mixture was evaporated (40° C. and 2.7 kPa) and the residue was heated at reflux temperature with ethanol (30 ml) for 45 minutes. The mixture was cooled to room temperature then evaporated and the residue was triturated with diethyl ether (100 ml) for 20 hours affording the title compound (4.3 g) as a white solid. TLC: RF=25/70 [on silica plates eluting with a mixture of dichloromethane and methanol, (90:10, v/v)]. 1H-NMR [400 MHz, (CD3)2SO]: δ 1.09 (t, J=7 Hz, 3H); 3.25 to 3.85 (3 m, 6H); 4.05 (m, 2H); 7.76 (d, J=8.5 Hz, 2H); 8.24 (d, J=8.5 Hz, 2H); 9.90 (b, 2H). MS (EI): 264[M]+.

Provenance & Evidence