Diisobutylaluminumhydride → (3,5-Diethoxy-4-pyrrol-1-yl-phenyl)-methanol

Beteiligte Stoffe

Reaktionsschritte

To a solution of 3,5-diethoxy-4-pyrrol-1-yl-benzoic acid ethyl ester (1.51 g, 4.98 mmol, 1.0 equiv) in toluene (5 mL) was added slowly over a time period of 15 min under slight cooling to 20° C. a solution of diisobutylaluminum hydride (8.9 mL, 12.45 mmol, 2.5 equiv; 20% solution in toluene). After 1 h, the excess of hydride was quenched by cautious addition of water (10 mL) and a 28% solution of NaOH (2 mL). The mixture was stirred for 30 min and the organic phase filtered over Hyflo Super Cel. The aqueous layer was extracted with toluene (2×50 mL), the combined organic phases washed with a sat. solution of NaCl (2×50 mL) and concentrated by evaporation under reduced pressure to afford 1.30 g (100%) of (3,5-diethoxy-4-pyrrol-1-yl-phenyl)-methanol. The crude alcohol (1.30 g, 4.98 mmol, 1.0 equiv) was dissolved in toluene (20 mL), and activated MnO2 (7.79 g, 89.5 mmol, 18.0 equiv) was added. The reaction mixture was heated to reflux for 7 h, after which time the reaction mixture was filtered through Hyflo Super Cel and concentrated yielding 1.15 g (89% yield) of the title compound. 1H NMR (300 MHz, DMSO): δ 1.17 (t, J=7.0 Hz, 6H), 4.02 (q, J=7.0 Hz, 4H), 6.08-6.09 (m, 2H), 6.75-6.76 (m, 2H), 7.25 (s, 2H), 9.89 (s, 1H). MS (ISP): 260.1 [M+H]+.

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