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0 °C

A solution of tert-butyl 4-(5-bromo-2-hydroxy-3-nitrobenzylidene)piperidine-1-carboxylate (2.1 g, 4.9 mmol) in methanol (150 mL) was stirred under atmospheric hydrogen in the presence of 10% palladium on charcoal (0.5 g) for 4 h. The catalyst was removed by filtration and the filtrate was evaporated in vacuo to give a crude oil (1.8 g) which was taken up in 2-butanone (30 mL) and aqueous sodium hydrogen carbonate (1.3 g in water 20 mL). Chloroacetyl chloride (0.78 g) was added dropwise at 0° C. The mixture was stirred at 0° C. for further 2 h and then at 80° C. for 4 h. It was partitioned between water (50 mL) and ethyl acetate (100 mL). The organic layer was evaporated in vacuo. Silica gel chromatography of the resulting residue eluting with ethyl acetate in petroleum ether (20–30%) gave the title compound (1.5 g) as an oil.

1. customThe catalyst was removed by filtration
2. customthe filtrate was evaporated in vacuo
3. customto give a crude oil (1.8 g) which
4. waitat 80° C. for 4 h
5. customIt was partitioned between water (50 mL) and ethyl acetate (100 mL)
6. customThe organic layer was evaporated in vacuo
7. washSilica gel chromatography of the resulting residue eluting with ethyl acetate in petroleum ether (20–30%)