Lithium Hydroxide → 5-(1,1-Dimethylethyl) 6,7-dihydroisoxazolo[4,5-c]pyridine-3,5(4H)-dicarboxylate

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Reaction Steps

A mixture of 7.31 g (25 mmol) of 6,7-dihydro-4H-isoxazolo[4,5-c]pyridine-3,5-dicarboxylic acid 3-ethyl ester 5-tert-butyl ester (E), 43 g (30 mmol) of lithium hydroxide and 75 mL of EtOH was stirred at RT for 12 h. The solvent was removed under a vacuum and the residue redissolved in a mixture of water/citric acid (pH=4) and ether. The organic phase was separated off, dried over magnesium sulfate and the solvent was removed under a vacuum. 6.65 g (99% of theoretical) of the desired product 6,7-dihydro-4H-isoxazolo[4,5-c]pyridine-3,5-dicarboxylic acid 5-tert-butyl ester (F) were obtained in the form of a yellow oil which crystallised at RT.

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