Dimethyl methylphosphonate → Dimethyl (3,3-dimethyl-2-oxoheptyl)phosphonate

Participants

Reaction Steps

Under argon atmosphere, anhydrous THF (120 ml) and dimethyl methylphosphonate (6.5 ml, 60.3 mmol) were cooled to -78° C. After 20 minutes n-butyl lithium (1.62N, 35.7 ml, 57.8 mmol) was added and the mixture was stirred for 30 minutes. Then, ethyl 2,2-dimethylpentanoate (3.81 g, 24.1 mmol) dissolved in 7 ml anhydrous THF was added, and the reaction mixture was stirred at -78° C. for 30 minutes and then at room temperature for 30 minutes. After acidification with acetic acid, THF was distilled off and the residue was extracted with ethyl acetate (150 ml×3). The combined organic layers were washed with water (100 ml) and with brine (100 ml), dried over anhydrous sodium sulfate, and concentrated to give a colorless oily product. Vacuum distillation of the product gave dimethyl 3,3-dimethyl-2-oxo-heptylphosphonate (4.61 g, 19.5 mmol, 81.1%, b.p.: 127°-130° C./ 0.7 mmHg). The structure was identified by the following data.

Provenance & Evidence