Selenium Dioxide → 6-chloro-3-methoxy-1-trityl-1H-pyrazolo[4,3-c]pyridine-4-carbaldehyde

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Reaction Steps

6-chloro-3-methoxy-4-methyl-1-trityl-1H-pyrazolo[4,3-c]pyridine (25 g, 45.5 mmol) was charged with 1,4-dioxane (200 ml) and selenium dioxide (15.13 g, 136 mmol) and heated to reflux overnight. The white slurry eventually dissolved to a dark yellow solution. TLC and LC/MS showed good conversion to product, with some SM left. The reaction was filtered through celite, washed with DCM and purified on silica gel, 10-50% EtOAc/hexanes to provide 6-chloro-3-methoxy-1-trityl-1H-pyrazolo[4,3-c]pyridine-4-carbaldehyde (15.7 g, 34.6 mmol, 76% yield).

Provenance & Evidence