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

Temperature

-78 °C

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.

1. stirringthe mixture was further stirred for 30 minutes
2. stirringThe reaction mixture was stirred at -78° C. for 30 minutes
3. concentrationAfter concentration, water (20 ml)
4. additionwas added to the residue
5. extractionthe mixture was extracted with ethyl acetate (100 ml×2)
6. washwashed with water (20 ml) and with brine (20 ml)
7. dry with materialdried over anhydrous sodium sulfate
8. concentrationto concentrate
9. distillationVacuum distillation of the residue (b.p.=108°-110° C. at 0.15 mmHg)

ORD record

ord-34efe78fbf7e4466a32b673538fdf7e1

Source dataset

uspto-grants-1989_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04880939