N-methyl-2-pyrrolidone → (S)-8-Nitro-2,3,3a,4-tetrahydro-1H-5-oxa-10b-aza-benzo[e]azulen-6-one

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Reaction Conditions

Reaction Steps

By adopting a similar procedure as described in “Mueller, W; Stauss, U.; Forschungsinst, W.; Bern, S. Helvetica Chimica Acta 1982, 65, 2118.” (S)-8-Nitro-2,3,3a,4-tetrahydro-1H-5-oxa-10b-aza-benzo[e]azulen-6-one was prepared as follows. A mixture of 2-fluoro-5-nitro-benzoic acid ethyl ester (1.16 g, 5.44 mmol.), S-prolinol (638 mg, 6.31 mmol) and diisopropylethylamine (1.5 mL, 8.62 mmol) in dry NMP (20 mL) was stirred at 100° C. for 3 h. Solvent was removed and the mixture was partition between EtOAc and water. Organic layer was extracted two more times with EtOAc. Combined organic was washed successively with water (twice) and brine. After drying over magnesium sulfate, solvent was evaporated. The product, (S)-8-Nitro-2,3,3a,4-tetrahydro-1H-5-oxa-10b-aza-benzo[e]azulen-6-one was obtained as a solid (1.08 g, 80%).

Provenance & Evidence