Sulfuric Acid → 4-Hydroxymethylpyrazolo[1,5-a]pyridine-2-carboxylic acid

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Reaction Steps

In Scheme I, dicarboxylic acid dimethyl ester 1 is prepared by reaction of the 3-pyridylcarbinol analogue with O-mesitylenesulfonylhydroxylamine in the presence of acetylene dicarboxylic acid dimethyl ester. Reaction of 1 with aqueous H2SO4 affords the 4-hydroxymethylpyrazolo[1,5-a]pyridine-2-carboxylic acid analogue, which is converted to the ethyl ester 2 by reaction with acetyl chloride in absolute ethanol. Oxidation of 2 with Jones reagent yields carboxylic acid 3, which is converted to amide 4 by reaction with an appropriate amine in the presence of BOP.

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