Carbon Tetrachloride → 1,1-Dimethylethyl 4-[4,5-dihydro-4-(methoxycarbonyl)-2-oxazolyl)-1-piperidinecarboxylate

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Reaction Steps

To a solution of 1,1-dimethylethyl 4-[[[1-(hydroxymethyl)-2-methoxy-2-oxoethyl]amino]carbonyl]-1-piperidinecarboxylate (i.e. the product of Example 7, Step A) (6.58 g, 19.92 mmol) in 70 mL of dry acetonitrile and 20 mL of dry dichloromethane was added triphenylphosphine (7.8 g, 29.87 mmol) and then 4.12 g (31.87 mmol) of N,N-diisopropylethylamine. The reaction mixture was stirred until homogeneous, and 4.59 g (29.87 mmol) of carbon tetrachloride was added dropwise over 5 minutes. The reaction mixture was stirred for 2.5 h at room temperature, cooled to 0° C. and diluted with 170 mL of ethyl acetate followed by 50 mL of saturated aqueous sodium bicarbonate solution. The mixture was stirred for 10 minutes, poured into 120 mL of water, and the organic layer was separated, washed with brine, dried over MgSO4 and concentrated under reduced pressure to give a yellow oil. The oil was purified by silica gel chromatography using 75-100% ethyl acetate in hexanes as eluant to give 2.95 g of the title compound as an oil containing traces of triphenylphosphine.

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