反应详情

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).

1. temperaturewhile cooling with an ice bath
2. additionare added dropwise
3. temperaturewhile cooling with an ice bath
4. stirringThe reaction mixture is stirred overnight at ambient temperature
5. stirringstirred for another day at ambient temperature
6. customThen the reaction mixture is evaporated down in vacuo at 60° C.
7. additionadded to 800 ml ice water
8. extractionThe aqueous phase is extracted with ethyl acetate
9. washthe combined extracts are washed with water and saturated sodium chloride solution
10. dry with materialdried over magnesium sulphate
11. customevaporated
12. stirringThe residue is stirred with diethyl ether, while 2-nitro-4-benzyloxy-5-(tetrahydropyran-4-yloxy)-benzoic acid
13. customcrystallises out as a by-product
14. filtrationThis is filtered off
15. customthe filtrate is evaporated down
16. customis saponified without any further purification