反应详情

Toluene-4-sulfonic acid (2R)-7-amino-8-(hydroximino-methyl)-2,3-dihydrobenzo[1,4]dioxin-2-ylmethyl ester (3.0 g, 7.9 mmole) was suspended in triethyl orthoformate under nitrogen, brought to a rapid boil and refluxed for 18 hours. The reaction mixture was cooled and the solvent evaporated. The residue was dissolved in methylene chloride (100 mL) and the solution obtained was washed with saturated sodium chloride (100 mL), dried over magnesium sulfate and evaporated to a brown gum (2.7 g) which contained several impurities. Chromatography on silica gel using 1% methanol in chloroform and then 3% methanol in chloroform as eluants gave 0.9 g (30%) of the (R)-enantiomer of the title compound as an oil. 1H(DMSO-d6) singlet, 9.01 δ(1 H); singlet, 9.19 δ(1 H); doublet, 7.75 δ(2 H); doublet, 7.60 δ(1 H); doublet, 7.50 δ(1 H) doublet, 7.30 δ(2 H); multiplet, 4.75 δ(1 H); double doublet, 4.51 δ(1 H); double doublet, 4.46 δ(1 H) double doublet: 4.32 δ(1 H); double doublet, 4.22 δ(1 H); singlet, 2.32 δ(3 H).

1. temperaturerefluxed for 18 hours
2. temperatureThe reaction mixture was cooled
3. customthe solvent evaporated
4. dissolutionThe residue was dissolved in methylene chloride (100 mL)
5. customthe solution obtained
6. washwas washed with saturated sodium chloride (100 mL)
7. dry with materialdried over magnesium sulfate
8. customevaporated to a brown gum (2.7 g) which