Phosphoryl-stabilized anions

Wadsworth, W.S., Synthetic applications of phosphoryl-stabilized anions, Org. React., 25, 73, 1977. 

Phosphoryl-stabilized anions, 25, 2 Photochemical cycloadditions, 44, 2 Photocyclization of stilbenes, 30, 1 Photooxygenation of olefins, 20, 2 Photosensitizers, 20, 2 Pictet-Spengler reaction, 6, 3 Pig liver esterase, 37, 1 Polonovski reaction, 39, 2... 

Wadsworth, W. S. Jr. Synthetic applications of phosphoryl-stabilized anions. In Dauben, W. G., Ed.-in-Chief "Organic Reactions", Vol. John Wiley Sons, Inc. New York, 1977 pp. 73-253. 

W. S. Wadsworth, Jr., Synthetic Applications of Phosphoryl-Stabilized Anions, Org. React. 1977, 25, 73-253. 

Several innovations have significantly extended the scope and synthetic utility of the classical Michaelis-Becker phosphonoacetate preparation. Eor example, the coupling of the Michaelis-Becker and Homer-Wadsworth-Emmons reactions for the synthesis of a-substituted acrylic acids represents a useful modification. According to Scheme 8.10, Michaelis-Becker alkylation of a dialkyl phosphite with a haloacetic acid in the presence of 3 eq of a base (one to neutralize the carboxyl group, one to form the phosphite conjugate base, and one to deprotonate the initially formed alkylation product) leads to the phosphoryl-stabilized anion directly. Treatment of the anion... 

This Wittig reaction was useful not only for the economical synthesis of retinoids but also subsequently as an excellent general method for the synthesis of carotenoids (Kienzle, 1976). Using the Wittig reaction, Pommer et al. revolutionized polyene chemistry, providing it with a variety otherwise scarcely imaginable (Weedon, 1976). New modified reagents, such as phosphoryl-stabilized anions (Homer et al., 1959 Stilz and Pommer, 1961 Wadsworth, 1977), and modified reaction conditions, such as the use of oxiranes as bases (Buddms, 1974), substantially increased the spectrum of possible syntheses of retinoids and carotenoids. 

A convenient route to trivinylphosphine has been developed by thiol elimination from tris[2-(phenylthio)ethyl]phosphine oxide.56 The reaction mechanism involves a phosphoryl-stabilized carbanion, from which benzene thiolate anion is eliminated. 

In addition, the high charge density on Mg2+ ensures that it is an excellent Lewis acid in reactions notably involving phosphoryl transfers and hydrolysis of phosphoesters. Typically, Mg2+ functions as a Lewis acid, either by activating a bound nucleophile to a more reactive anionic form (e.g. water to hydroxide anion) or by stabilizing an intermediate. 

The synthesis of alkenes through the Wittig reaction has generated an impressive understanding of the chemistry of organophosphorus compounds. The generated car-banions stabilized by a phosphoryl moiety can be considered as ylide anions, and the... 

Suelter90 has classified enzymes that are activated by monovalent cations into two groups. One involves the catalysis of phosphoryl-transfer reactions and the other a variety of elimination and/or hydrolytic reactions in which a keto-enol tautomer can be invoked as an intermediate. The M+ cation is then required to stabilize the enolate anion. It is still not possible to verify this hypothesis, but it seems unlikely in view of the comments above. 

Stabilization of enolate anions generated from abstraction of a proton a to a carboxylate Hydrolysis, phosphoryl group transfer via hydrolytic nucleophilic substitution Stabilization of diverse oxyanion intermediates via metal-assisted catalysis Schiff base dependent formation of an electron sink ... 

Figure 1 Chemical mechanism of DNA polymerase and 3 -5 exonuclease, (a) DNA polymerase reaction. The enzyme chelates two metal Ions using three aspartic acid residues (only two are shown). Metal ion A abstracts the 3 hydroxyl proton of the primer terminus to generate a nucleophile that attacks the a-phosphate of an incoming dNTP substrate. The phosphoryl transfer results In production of a pyrophosphate leaving group, which is stabilized by metal Ion B. (b) The 3 -5 exonuclease proofreading activity is located in a site that is distinct from the polymerase site yet it uses two-metal-ion chemistry similar to DNA synthesis. The reaction type is hydrolysis in which metal ion A activates water to form the hydroxy anion nucleophile. Nucleophile attack on the phosphate of the mismatched nucleotide releases it as dNMP (dGMP in the case shown).

---