Trifluoroacetic acid → 3-(8-Chloro-3-methoxy-2,5-dioxo-2,5-dihydro-1H-benzo[b]azepin-4-yl)acrylic Acid

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Reaction Steps

4-[2-(Tert-butoxycarbonyl)ethenyl]-8-chloro-3-methoxy-2,5-dioxo-2,5-dihydro-1H-benz[b]azepine (0.3455 g) was dissolved in dry methylene chloride (7.5 mL) under argon. The solution was treated with trifluoroacetic acid (7 mL). The solution was stirred at room temperature for 30 minutes. The solution was concentrated under water aspirator vacuum and then it was dried under high vacuum to give a white solid. The solid was dissolved in 125 mL of hot methanol. The solution was filtered and concentrated to 80 mL volume as a white solid formed. It was cooled in an ice bath and the solid was filtered off, washed with cold methanol, and air-dried to give a white solid (0.162 g); mp 281.4°-282.0° C. (dec); 1H NMR (d6 -DMSO) 7.54 (d,1, J=16), 6.52 (d,1, J=16) for trans olefin protons; MS: m/z=308. Analysis for C14H10ClNO5 : Calculated: C, 54.65; H, 3.28; N, 4.55; Found: C, 54.36; H, 3.14; N, 4.37.

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