[CH2:1]1[O:11][C:4]2([CH2:9][CH2:8][C:7](=[O:10])[CH2:6][CH2:5]2)[O:3][CH2:2]1.C[Si]([N-][Si](C)(C)C)(C)C.[Li+].C([C:24]([O:26][CH2:27][CH3:28])=[O:25])#N.CCOC(C)=O>C1COCC1.O>[CH2:27]([O:26][C:24]([CH:8]1[C:7](=[O:10])[CH2:6][CH2:5][C:4]2([O:3][CH2:2][CH2:1][O:11]2)[CH2:9]1)=[O:25])[CH3:28]1,4-Cyclohexanedione mono-ethylene ketal (25 g) was dissolved in THF and cooled to −78° C. 1.0 M Lithium bis(trimethylsily)amide (160 mL) in THF was added dropwise. After 30 min, ethyl cyanoformate (15.9 mL) was added dropwise. After 60 min, the solution was poured into EtOAc and water containing ice. The organic layer was washed with water and brine before it was dried and concentrated. This crude was filtered through a plug of silica to give the 8-oxo-1,4-dioxa-spiro[4.5]decane-7-carboxylic acid ethyl ester (32.4 g). MS found: (M+H)+=228.9.
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