Hexane → Dimethyl (3-methyl-2-oxooct-5-yn-1-yl)phosphonate

Participants

Reaction Conditions

Reaction Steps

Under argon atmosphere, to a stirred solution of dimethyl methylphosphonate (7.91 ml, 0.074 mol) in anhydrous THF (150 ml) was added dropwise a solution of n-butyl lithium in hexane (1.71N, 43 ml, 0.074 mol) and the mixture was stirred for 30 min at -78° C. A solution of ethyl 2-methyl-4-heptynoate (5.0 g, 0.03 mol) in anhydrous THF (5 ml) was dropwise added into the mixture, and the resulting mixture was stirred for 30 min. at -78° C. The resulting mixture was allowed to room temperature and 30 min. later, to the solution were then added water (10 ml) and acetic acid (45 ml) under ice-cooling, and concentrated. The residue was diluted with water (20 ml) and extracted with ethyl acetate (50 ml×2). The combined ethyl acetate layers were washed with water (20 ml) and with brine (20 ml), dried over anhydrous sodium sulfate, and concentrated. The residue was distilled to give dimethyl 3-methyl-2-oxo-5-octynylphosphonate (6.55 g, 0.027 mol, 88%, B.p.: 118°-121° C./0.35 mmHg). The product was assigned the structure by the following data.

Provenance & Evidence