Phosphonic acid bisamides

The (E/Z) ratio of the product can often be changed by a change in solvent or by the addition of salts. Another way of controlling the stereochemistry of the product is by use of the aforementioned phosphonic acid bisamides. In this case the betaine (42) does form and when treated with water gives the (3-hydroxyphosphonic... 

Ylides formed from phosphinoxides Ar2PCHRR phosphonic acid bisamides... 

Corey, E. J., Kwiatkowski, G. T. Synthesis of olefins from carbonyl compounds and phosphonic acid bisamides. J. Am. Chem. Soc. 1966, 88, 5652-5653. 

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