Iodoethane → ethyl 3,4-dihydro-2H-pyran-2-carboxylate
反応式
[CH:1]12[CH2:8][CH2:7][CH:4]([O:5][CH2:6]1)[C:3](=[O:9])[O:2]2.O1C=CC[CH2:12][CH:11]1C([O-])=O.[Na+].C(I)C>CN(C)C=O>[O:5]1[CH:6]=[CH:1][CH2:8][CH2:7][CH:4]1[C:3]([O:2][CH2:11][CH3:12])=[O:9]参加物
5
実験手順
The synthesis of 2,5-dioxabicyclo[2.2.2]octan-3 one was achieved through a three step reaction sequence as illustrated below: ##STR3## Sodium 3,4-dihydro-2H-Pyran-2-carboxylate was esterified with ethyl iodide in dimethylformamide to afford ethyl 3,4-dihydro-2H-pyran-2-carboxylate. Subsequent hydroboration with a borane solution in tetrahydropyran at 0° C., followed by oxidation with a sodium dichromate-sulfuric acid aqueous solution and subsequent treatment with sodium hydrogen sulfite gave ethyl 5-hydroxytetrahydropyran-2-carboxylate as a stereoisomer mixture. The hydroxytetrahydropyran ester was heated in a dilute solution in the presence of a catalytic amount of p-toluenesulfonic acid, any ethyl alcohol being liberated was removed through a Soxhlet extractor containing type 5A molecular sieves. Column chromatographic separation of the reaction products and subsequent repeated recrystallization gave the bicyclic lactone as colorless crystals; the overall yield was approximately 20%.