Water → (S)-1-[2-(Acetyloxy)-1-phenylethyl]-2,5-dihydro-1H-pyrrol-2,5-dione

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Reaction Steps

1,3-Bis(trimethylsilyl)urea (0.745 g, 3.65 mM) was added to (S)-(+)-2-phenylglycinol (0.5 g, 3.65 mM) dissolved in THF (10 ml, distilled from Na/benzophenone). The mixture was refluxed for 1 hr. A precipitate formed. Maleic anhydride (0.376 g, 3.83 mM) was added and the mixture was refluxed for 0.5 hr. H2O (66 μl, 3.65 mM) was added to the cooled mixture and stirred for 30 min. to form the intermediate ##STR46## which was not recovered from the reaction mixture. Tetrabutyl-ammonium fluoride (TBAF.3H2O, 0.115 g, 0.365 mM), acetic anhydride (Ac2O) (3.44 ml, 36.5 mM), and TEA (3.0 ml, 21.9 mM) were added and the mixture refluxed for 2.5 hrs. After cooling to room temperature, H2O (15 ml) was added and stirred for 1 hr. The reaction mixture was taken up in EtOAc (75 ml), washed with water (2×50 ml), 5% NaHCO3 (50 ml), brine (25 ml), dried (MgSO4), and evaporated to a black oil: 0.88 g. The oil was Kugalrohr distilled under vacuum (~0.3 mm), oven temperature 110°-30°, giving the title compound as a colorless oil: 0.79 g (83% yield). TLC (silica gel, EtOAc/hexane 7:3 visualized with UV and KMnO4) showed the product as one spot at Rf 0.60.

Provenance & Evidence