Dichloromethylphosphonates

Glaxo employed a bidentate catalyst, pyridinium dichloromethylphosphonate, in... 

Canan. J., Waschbiisch, R., Marinetti, A., and Savignac, P, An improved synthesis of dichloroalkyl-phosphonates, chloroalkynes and terminal alkynes via diethyl dichloromethylphosphonate. Synthesis, 1494, 1996. 

Dichloromethylphosphonic dichloride can be readily obtained by the reaction of CHCl, PCI, and AICI3 and subsequent hydrolysis (63-70% yields). 35.235.236 Esterification with alcohols- or substituted phenols in the presence of bases gives the corresponding dichloromethylphosphonates in 70-81% yields (Scheme 3.36). 

Diethyl methylphosphonate reacts with phenylsulfonyl chloride (2 eq) in the presence of n-BuLi (3 eq) to produce diethyl 1-lithio-1,1-dichloromethylphosphonate, which can be quenched in quantitative yield or reacted directly with a large variety of carbonyl compounds (Homer-Wadsworth-Eimnons reaction), thus providing a useful one-pot process for the synthesis of dichloroalkenes. ... 

Diethyl 2-oxopropylphosphonate may be treated with excess SO2CI2 in CH2CI228 or molecular chlorine in CCI42 to obtain diethyl l,l-dichloro-2-oxopropylphosphonate in 93% yield. However, the extent of chlorination cannot be easily controlled, and the reaction of substituted methylphos-phonates with SO2CI2 generally gives a mixture of mono- and dichloromethylphosphonates.2 -29s... 

A different approach involving the abstraction of a chlorine atom from diethyl trichloromethylphosphonate by means of PtNMejIs in CgHg at room temperature in the presence of McsSiCl gives diethyl l-(trimethylsilyl)-l,l-dichloromethylphosphonate in 90% yield.- °... 

Savignac, P, Dreux, M., and Coutrot, P., Halogen-metal exchange. Synthesis of dichloromethylphosphonates, Tetrahedron Lett., 16, 609, 1975. 

Diethyl 1-chloroalkylphosphonates 2 are key reagents for the preparation of different organic compounds. The diethyl 1-chloromethylphosphonate reacts readily with butylli-tium to give diethyl a-lithiochloromethylphosphonate, which on treatment with tetra-chloromethane gives the stable diethyl 1,1-dichloromethylphosphonate. The latter is suitable for the preparation of 1,1-dichloroalkenes [242 a,b]. 

Diisopropyl chloromethylphosphonate allowed to react at -78° with n-butyl-lithium in tetrahydrofuran, then with CCI4 at the same temp. diisopropyl dichloromethylphosphonate. Y 90-95%. F. e., chlorinating agent, and limitation s. P. Savignac, M. Dreux, and P. Coutrot, Tetrah. Let. 1975, 609 also a,) -ethylene-cfalorides by subsequent Horner synthesis s. Synthesis 1975, 658. 

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