Acetic Acid → Dimethyl (3,3-dimethyl-2-oxohept-5-yn-1-yl)phosphonate

Participants

Reaction Conditions

Reaction Steps

Under argon atmosphere, a solution of n-butyllithium in hexane (1.64 N, 33 ml, 0.054 mol) was slowly added dropwise to a solution of dimethyl methylphosphonate (6.82 g, 0.055 mol) in anhydrous THF (100 ml) with stirring at -78° C., and the mixture was further stirred for 30 minutes. To the reaction mixture, there was added dropwise a solution of ethyl 2,2-dimethyl-4-hexynoate (3.7 g, 0.022 mol) in anhydrous THF (15 ml). The reaction mixture was stirred at -78° C. for 30 minutes and then at room temperature for one hour. Acetic acid (3.1 ml, 0.054 mol) and water (10 ml) were added to the reaction mixture. After concentration, water (20 ml) was added to the residue and the mixture was extracted with ethyl acetate (100 ml×2). The organic layers were combined, washed with water (20 ml) and with brine (20 ml), and dried over anhydrous sodium sulfate to concentrate. Vacuum distillation of the residue (b.p.=108°-110° C. at 0.15 mmHg) gave dimethyl 3,3-dimethyl-2-oxo-5-heptynylphosphonate (5.04 g, 0.020 mol, 93% yield). The structure was confirmed by the following data.

Provenance & Evidence