CID 406 → Diethyl 1-methoxy-1-(4-chloro-3-methoxyphenyl)methane phosphonate

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Reaction Steps

A solution of dimethyl acetal 3 (4.3 g, 20 mmol), sieve-dried CH2Cl2 (20 ml) and triethyl phosphite (4.1 ml, 24 mmol) was stirred under argon at -78° C. Boron trifluoride ethereats (2.95 ml, 24 mmol) was added dropwise at -78° C., the solution was stirred 5 min and stored overnight at -20° C. The next day the reaction was warmed to room temperature and stirred 5 hours to complete phosphonate formation. With vigorous stirring, the reaction was quenched with solid NaHCO3 followed by 40 ml saturated NaHCO3 solution. After gas evolution ceased, 40 ml CH2Cl2 and 20 ml H2O were added, the biphasic mixture was partitioned and the CH2Cl2 phase was recovered, dried over Na2SO4 and evaporated. After pumping in vacuo, the oil was purified on a silica gel plug, eluting with CH2Cl2 to yield phosphonate 4 as a light yellow oil (6.01 g., 99%).

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