Dimethylformamide dimethyl acetal → 4-[2-(1-Ethyl-4,5-dihydro-imidazol-2-yl)ethyl]-1-piperidine carboxaldehyde dimethylacetal

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Reaction Steps

A solution of 4-[2-(1-ethyl-4,5-dihydro-imidazol-2-yl)ethyl]piperidine (0.66 g, 0.0031M) in methanol (6 ml) and dimethylformamide dimethylacetal (6 ml) was heated at 90° C. for 6 hrs. Removal of the excess of dimethylformamide dimethylacetal gave 4-[2-(1-ethyl-4,5-dihydro-imidazol-2-yl)ethyl]-1-piperidine carboxaldehyde dimethylacetal. The solution of the piperidine carboxaldehyde dimethylacetal in chloroform (5 ml) was then added to a mixture of 6-aminopenicillanic acid (0.6 g, 0.0028M) and diisopropylethylamine (0.5 ml) in chloroform (6 ml) at 0° C. The reaction was stirred at 0° C. for 1 hr and room temperature for 3 hrs. The solvent was removed and water (10 ml) was added. After being washed with ethylacetate, the aqueous solution, acidified from about pH 3 to about 3.5 was purified on Sephadex LH 20 columns to give [2S-(2alpha,5alpha,6beta)] -6-[[[4-[2-(1-ethyl-4,5-dihydro-1H-imidazol-2-yl)ethyl]-1-piperidinyl]methylene]amino-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid hydrochloride (0.46 g, 35% yield).

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