2,6-Dichloroisonicotinic acid → tert-Butyl 2,6-dichloropyridine-4-carboxylate

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Reaction Steps

To a solution of 2,6-dichloropyridine-4-carboxylic acid (8.28 g, 43.1 mmol, Aldrich) in dry THF (30 ml) was added N,N′-diisopropyl-O-t-butylisourea (17 ml, 3.6 M) dropwise over 1 minute. The resulting mixture was stirred at room temperature overnight. The material was then heated to 65° C. and additional N,N′-diisopropyl-O-t-butylisourea (10 ml) was added dropwise. The mixture was stirred for 1 hour and cooled to room temperature. After removing volatiles, the remainder was purified by flash silica gel column (EtOAc/hexanes 5:95 followed by 7.5:92.5) affording tert-butyl-2,6dichloro-4-pyridine carboxylate (7.83 g, 73%) as a white solid. MS (ES+): 248.

Provenance & Evidence