Lithium Hydroxide → 6-(6-Oxo-2-thioxo-1,2,3,6-tetrahydro-pyrimidin-4-ylmethyl)-naphthalene-1-carboxylic acid

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Reaction Conditions

Reaction Steps

3.46 g (45.4 mMol) thiourea are added to a solution of 29.7 mMol 6-(3-ethoxycarbonyl-2-oxo-propyl)-naphthalene-1-carboxylic acid methyl ester in 25 ml tert-butanol. Then 13.3 g (119 mMol) potassium tert-butyrate are added (exothermic). After 50 min, the mixture is heated for 4.5 h in an oil bath of 100° C. Cooling to rt gives an almost solid mixture, which is redissolved by addition of 59 ml of a 1 M aq. solution of LiOH and stirring during 40 min. This solution is diluted with 500 ml of a 0.33 M solution of NaOH and EtOAc. The organic phase is separated off, washed with 300 ml of a 0.33 M solution of NaOH and discarded. The aq. phases are acidified by addition of 2 N HCl (pH=3), the precipitated product filtered off, washed with 0.001 N HCl and dried in vacuo at 80° C. The crude material is stirred in a boiling mixture of 0.6 l CH3CN, 60 ml EtOAc, 120 ml MeOH and 120 ml THF. Filtration of the hot suspension then leads to the title compound: m.p.: 334-337° C.

Provenance & Evidence