Potassium Hydroxide → 1-Methyl-2,4,5,6-tetrahydrocyclopenta[c]pyrrole

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Reaction Conditions

Reaction Steps

A solution of ethyl 3-methyl-2,4,5,6-tetrahydrocyclopenta[c]pyrrolecarboxylate 4j (9.1 g, 0.04mol) and potassium hydroxide (26 g, 0.47 mol) in ethanol (200 ml) was heated at 80° C. for 4 hours and concentrated. The residue was combined with ice water (400 ml), and made slightly acidic by the additionof acetic acid to bring about the precipitation of crude 3-methyl-2,4,5,6-tetrahydrocyclopenta[c]pyrrolecarboxylic acid. The crude acid was combined with ethanolamine (5 g), heated at 180° C. for 1 hour, and diluted with ice water (100 ml). Extraction by methylene chloride (3×100 ml) followed by solvent removal and distillation of a residual oil, bp 110°-111° C. (20 mm) gave 3-methyl-2,4,5,6-tetrahydrocyclopenta[c]pyrrole 5j, 3.6 g (64%) as a colorless oil; 1H NMR (CDCl3): δ 7.57 (s, 1H), 6.33 (s, 1H), 2.67 (t, 2H), 2.59 (t7 2H), 2.35 (m, 2H), 2.22 (s, 3H). Anal. calcd for C8H11N: C, 79.34; H, 9.09; N, 11.59. Found: C, 79.12; H, 9.29; N, 11.60.

Provenance & Evidence