Selected Applications of Phosphonate Carbanions

Although the magnesium salt (127 M = iMg) could be alkylated and acylated on carbon, the potassium salt (127 M = K) in ether-dioxan with chlorotrimethylsilane gave acetonitrile and the phosphate (128) as the only identifiable products from a reaction which may involve silylation of the ambident phosphonate carbanion on oxygen. Allylic phosphonate 

Whether a Michael or a Horner reaction occurs when an a)3-unsaturated ketone is treated with a phosphonate carbanion depends upon the conditions. Chalcone and the ester phosphonate (135) gave the product of a Horner reaction with sodium hydride in diglyme, but Michael addition occurred with sodamide in ether. 

The formation of deoxybenzoin on hydrolysis of the product obtained from benzonitrile and the benzylic phosphonate carbanion has been 

The same phosphonate with the anhydride (138) gave the phosphonate (139 X = CN), existing as the acid (139) in the solid and as an equilibrium between (139) and the lactone (140) in solution. The corresponding product from the ester phosphonate is the lactone (140 X = C02Et) both in the solid and in solution. 

Among interesting olefin syntheses with ester phosphonates are those with the allenic aldehydes (141) and with the steroidal epoxy-aldehyde (142). The yield of allenic carboxylic esters has been increased to 

General.—The relatively unreactive diethyl arylmethylphosphonates have been used quite successfully in alkene synthesis with phase-transfer catalysis.100 In a comparative study it was shown that anions derived from /S-ketophosphonamides (109) have very low reactivity whereas those from 0-ketophosphonates (110) react quite well with aldehydes to give frwjj-alkenes.101 Benzyl dimethyl phosphonoacetate (111) can be used to form alkenes, e.g. (112), from which the benzyl group can be removed by hydrogenolysis without disturbing the C=C bond.102 The carbanions (113) can be 

Reagents i, BuLi ii, CBr4-LiBr iii, LiNPa-LiBr iv, R1R2C=0. 

Among those phosphonates used successfully in alkene synthesis with aromatic aldehydes were (114),106 (115),107 (116),108(117),109 and(118).110 The stereochemical 

The synthesis of oc/S-unsaturated sulphoxides from the anion (122) has been described.113 The reaction is non-stereospecific, but good yields are obtained from cyclopentanones and acetophenones. Good yields of mono-alkylated products are obtained from the reaction of carbanions of diethyl 2-oxophosphonates (123) and reactive halides 114 alkylation of the compounds (124) has also been achieved.115 The 

Gernayova, J. Kovac, M. Dandarova, B. Hasova, and R. Palovcik, Coll. Czech. Chem. Comm., 1976,41, 764. 

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