[H-].[Na+].[CH3:3][O:4][CH:5]([O:15][CH3:16])[CH:6]([CH3:14])[CH2:7][CH2:8][CH:9]([OH:13])[CH:10]([CH3:12])[CH3:11].[H][H].[CH3:19]I>O1CCCC1.O.CN(C)P(=O)(N(C)C)N(C)C>[CH3:16][O:15][CH:5]([O:4][CH3:3])[CH:6]([CH3:14])[CH2:7][CH2:8][CH:9]([O:13][CH3:19])[CH:10]([CH3:12])[CH3:11]To a mixture of 2.4 g. of clean sodium hydride in 200 ml. of dry tetrahydrofuran containing 20 ml. of dry HMPT (hexamethylphosphorictriamide) is added dropwise a solution of 20.4 g. of 1,1-dimethoxy-5-hydroxy-2,6-dimethylheptane in dry tetrahydrofuran. A mixture is stirred at room temperature until evolution of hydrogen ceases and then 16 g. of methyl iodide is added. The reaction mixture is refluxed for 3 hours and then cooled, diluted with water and extracted with ether. The etheral extracts are evaporated under reduced pressure to yield crude 1,1,5-trimethoxy-2,6-dimethylheptane which can be purified by distillation or chromatography on Florisil.
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