Citric Acid → HCID 21925289, compound

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Reaction Steps

42.60 g potassium-tert.-butoxide are added to 38 ml of tetrahydrofuran-4-ol in 228 ml N,N-dimethylformamide while cooling with an ice bath. The mixture is stirred for one hour at ambient temperature, then 22.90 g 6-nitro-benzo[1,3]dioxol-5-carboxylic acid are added. After 1.5 hours the reaction is complete according to thin layer chromatography and 28.94 ml of benzylbromide are added dropwise while cooling with an ice bath. The reaction mixture is stirred overnight at ambient temperature, combined with 100 ml 10% citric acid and stirred for another day at ambient temperature. Then the reaction mixture is evaporated down in vacuo at 60° C. and added to 800 ml ice water. The aqueous phase is extracted with ethyl acetate and the combined extracts are washed with water and saturated sodium chloride solution, dried over magnesium sulphate and evaporated. The residue is stirred with diethyl ether, while 2-nitro-4-benzyloxy-5-(tetrahydropyran-4-yloxy)-benzoic acid crystallises out as a by-product. This is filtered off and the filtrate is evaporated down. The main product remaining is benzyl 2-nitro-4-benzyloxy-5-(tetrahydro-pyran-4-yloxy)-benzoate, which is saponified without any further purification to form carboxylic acid (see Example V).

Provenance & Evidence