Ethyl Acetate → Ethyl 6-(2,3-dichlorobenzyl)-1,4-dihydro-8-fluoro-1-[2-(tert-butyldimethylsilyloxy)ethyl]-4-oxo-3-quinolinecarboxylate

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Reaction Steps

Under an argon stream, 1M solution (2.9 ml, 2.9 mmol) of 2,3-dichlorobenzylzinc chloride in THF obtained in the same manner as in Reference Example 1 was added to THF (20 ml), and then bis(dibenzylideneacetone)palladium(0) (22 mg, 0.039 mmol), tri(2-furyl)phosphine (18 mg, 0.077 mmol) and ethyl 1,4-dihydro-8-fluoro-6-iodo-1-[2-(tert-butyldimethylsilyloxy)ethyl]-4-oxo-3-quinolinecarboxylate (1.0 g, 1.9 mmol) obtained in Step 4 were added. The mixture was stirred at room temperature for 17 hrs, and then a solution (1.0 ml, 1.0 mmol) of 2,3-dichlorobenzylzinc chloride in THF was added. The mixture was heated under reflux for 1 hr. After allowing the mixture to cool, saturated aqueous ammonium chloride solution was added to the reaction solution and insoluble materials were filtered off with Celite. The filtrate was extracted with ethyl acetate, and the organic layer was washed with water and saturated brine, and dried over sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure, and the obtained residue was purified by silica gel chromatography (ethyl acetate:hexane=1:1), and then by PTLC (ethyl acetate:chloroform=1:2) to give an object product (562 mg, yield 53%) as a pale-yellow oil.

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