2-Phenylethanol → 7-phenethylpyrazolo[3,4-b]pyrrolo[3,4-d]pyridine-6,8(3H,7H)-dione

Participants

Reaction Conditions

Reaction Steps

A solution of 3-(4-methoxybenzyl)pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine-6,8(3H,7H)-dione (150 mg, 0.48 mmol), phenethylalcohol (70 μl, 0.58 mmol) and triphenylphosphine (191 mg, 0.73 mmol) in anhydrous tetrahydrofuran (6 ml) was treated with diisopropyl azodicarboxylate (141 μl, 0.73 mmol) at room temperature and stirred for 6 hours. The mixture was partitioned between ethyl acetate (100 ml) and water (100 ml). The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to afford a brown oil. The oil was dissolved in trifluoroacetic acid (7 ml) and heated to 65° C. for 24 hours. The mixture was concentrated under reduced pressure and the product was partitioned between ethyl acetate (100 ml) and saturated aqueous sodium bicarbonate (50 ml). The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to afford a brown solid which was purified by flash column chromatography (12 g SiO2, 30% ethyl acetate in hexanes). Fractions containing the product were concentrated under reduced pressure. The solid was triturated in ethyl acetate, cooled to 0° C. and filtered to afford 7-phenethylpyrazolo[3,4-b]pyrrolo[3,4-d]pyridine-6,8(3H,7H)-dione as a white solid (18 mg, 13%). M.p.=237-239° C.; 400 MHz 1H NMR (DMSO-d6) δ: 9.00 (s, 1H), 8.51 (s, 1H), 7.23 (m, 6H), 3.85 (t, J=7.2 Hz, 2H), 2.95 (t, J=7.6 Hz, 2H); LCMS: 293 [M+H].

Provenance & Evidence