CID 406 → Dimethyl [2-oxo-3-(thiophen-2-yl)propyl]phosphonate

Participants

Reaction Steps

A solution of 37.2 g (0.3 mole) dimethyl methylphosphonate (Aldrich) in 400 ml dry tetrahydrofuran was cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution was added 194 ml of 1.6 M n-butyllithium in hexane solution (Alfa Inorganics, Inc.) dropwise over a period of 18 minutes at such a rate that the reaction temperature never rose above -65°. After an additional 5 minutes stirring at -78°, 23.4 g (0.15 mole) methyl 2-(2-thienyl)acetate was added dropwise at a rate that kept the reaction temperature less than -70° (20 minutes). After 3.5 hours at -78° the reaction mixture was allowed to warm to ambient temperature, neutralized with 6 ml acetic acid and rotary evaporated to a white gel. The gelatinous material was taken up in 75 ml water, the aqueous phase extracted with 100 ml portions of chloroform (3× the combined organic extracts were backwashed (50 ml H2O), dried (MgSO4), and concentrated (water aspirator) to a crude residue and distilled, b.p. 150°-52° (<0.5 mm) to give 4.8 g dimethyl 2-oxo-3(2-thienyl)propylphosphonate (2a).

Provenance & Evidence