Phthalimide → 2-(3-Bromo-6,7-dihydro-5H-cyclopenta[b]pyridin-7-yl)isoindoline-1,3-dione

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Reaction Steps

(rac)-3-Bromo-6,7-dihydro-5H-[1]pyrindin-7-ol (4.84 g, 22.6 mmol) and isoindoline-1,3-dione (3.66 g, 24.9 mmol) were dissolved in THF (130 ml); then, triphenylphosphine (7.41 g, 28.3 mmol) was added, followed by a solution of di-tert-butyl azodicarboxylate (6.25 g, 27.1 mmol) in THF (3.0 ml) below 5° C.; stirring at RT was then continued for 20 hours. The reaction mixture was concentrated in vacuo to give a crude product (23.507 g), which was purified by flash chromatography (silica gel, 100 g, 10% to 50% EtOAc in heptane) to give 2-((rac)-3-bromo-6,7-dihydro-5H-cyclopenta[b]pyridin-7-yl)isoindoline-1,3-dione (11.114 g, not pure). This intermediate was dissolved in ethanol (140 ml), then, while stirring, hydrazine hydrate (3.01 g, 2.95 ml, 75.1 mmol) was added and the reaction mixture was heated up to reflux. After 2 hours, it was poured into NaOH 1N (150 ml) and extracted with CH2Cl2 (2×100 ml). The organic layers were dried over MgSO4, filtered and concentrated in vacuo to give a crude product (8.845 g) which was purified by flash chromatography (silica gel, 100 g, 0% to 20% MeOH in CH2Cl2) to yield the title compound (1.80 g, 37%) as purple oil. MS: 213.0 (MH+, 1Br).

Provenance & Evidence