Dimethyl methylphosphonate → Dimethyl (2-oxo-6-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)hexyl)phosphonate

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Reaction Steps

A solution of dimethyl methylphosphonate (13.20 g, 106.5 mmol) in anhydrous THF (165 mL) was cooled to −78° and treated dropwise with 2.5 M n-BuLi (42.3 mL). After stirring at −78° for 45 min, a solution of ester 1-5 (6.6 g, 26.6 mmol) in THF (35 mL) was added dropwise and the resulting solution stirred for 30 min at −78°, quenched with sat. NH4Cl (100 mL), then extracted with ethyl acetate (3×150 mL). The combined organic extracts were dried (MgSO4), filtered, and concentrated to afford a yellow oil. Chromatography on silica gel (5% MeOH/CH2Cl2) afforded 1-6 as a yellow oil.

Provenance & Evidence