Synthetic Applications of Phosphonate Carbanions

A study of the decomposition in basic media of the erythro- and threo-isomers of the /8-hydroxyphosphonate (169) showed that the first step in the phosphonate olefin synthesis is reversible and that the diastereo-isomers of (169) can also interconvert directly, presumably via the a-car-banion. 

Among phosphonate esters (170) used in olefin synthesis were those with R = S-CeHi-Br-/ , S02 C6H4-Br-A CO-NHR, and S CHa CEi-XHa. The allyl vinyl thio-ethers (171) obtained using the last of these gave a-allyl-aldehydes on pyrolysis in the presence of red mercuric oxide. 

Enamine phosphonates (172) have been prepared by the addition of amines to alkynylphosphonates and used as shown in the synthesis of ajS-unsaturated ketones. The corresponding diphenylphosphine oxides have been prepared and used in a similar manner.  

Corey s phosphonamide olefin synthesis has been extended to the synthesis of vinyl ethers using the phosphonamides (Me2N)2P( O)- CHjOR. 

A new pteridine synthesis is based on the reaction of 4-amino-5-nitroso-pyrimidines with the phosphonate carbanions (173 = C02Et,  

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