A,P-Ethylenephosphonic acid esters

Cyclic a-amino-a,p-ethylenephosphonic acid esters from iminoester salts and dialkyl phosphites... 

A soln. of cyano(methylthio)methyltrimethylsilane in THF added over 5 min to a stirred soln. of LDA (1 M) in the same solvent at —78° under N2, treated dropwise after 30 min with a soln. of benzaldehyde in THF, the mixture stirred for 1 h, warmed slowly to room temp., and stirring continued for 3 h - product. Y 85% (E/Z mixture). The method is higher-yielding than the Wittig-Horner approach, and does not require strong base. F.e. with enolizable aldehydes and ketones s. D.I. Han, D.Y. Oh, Synth. Commun. 75, 2111-6 (1988) a-alkyIthio-a,p-ethylenephosphonic acid esters s. M. Mikotajczyk, P. Bafczewski, Synthesis 1989, 101-6. 

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