Wittig reaction extensive review

In later years this reaction became known as the aza-Wittig reaction and review articles appeared in the 1990s.i°2- 05 recent years the aza-lMttig reaction has been used extensively to synthesize complex heterocycles involving carbodiimides as intermediates. 

E,Z)-1,3-Dienes can also be readily prepared, with reasonable stereoselectivity, by routes involving the Wittig reaction but these have been recently extensively reviewed (.2,6, 7) and therefore will not be discussed here. 

Terminal phosphinidene-metal complexes, L TM=PR, readily add to double bonds (equation 17). Both metal-stabilized and phosphine-stabilized phosphinidenes, R P= PR3, can act as phospha-Wittig reagents, which undergo metathesis reactions with carbonyl-containing compounds to generate carbon phosphorus double bonds (equations 18 and 19). Pnictinidenes and their complexes have been extensively reviewed in terms of both their syntheses and reactivities. ... 

The Wittig reaction has been extensively reviewed. This section relied heavily on an excellent recent review that includes a discussion of the mechanism, see B. E. Maryanoff and A. B. Reitz, Chem. Rev., 1989, 89, 863. For additional reviews see ref. 115. 

The chemistry of carbanions stabilized by the heavy main group elements has been extensively investigated by Kauffmann, and a thorough description of his work can be found in a recent review. There are many similarities between the elements. The anions stabilized by the heavy main group elements listed above can generally be alkylated, and in some cases their reaction with carbonyl compounds is a useful alternative to the Wittig reaction. All the stabilized metallomethyl lithium anions (except bismuth) exhibit marked thermal stability. 

McMurry, Diels-Alder, Scholl, and Wittig reactions as well as zn fra molecular cyclodehydration procedures of carboxylic acids, oxidation of hydrogenated aromatics and reduction of quinones and phenols have already been extensively reviewed [26,30] and will be mentioned only in few exemplified syntheses of new parent aromatic systems or in those cases when significant modifications result in much improved yields and/or milder reaction conditions. 

The laboratory synthesis of unsaturated fatty acids has been pursued extensively. Whilst a few acids are easily isolated from appropriate natural sources (Section 4.9) it is necessary to resort to chemical synthesis when the acid occurs only in obscure sources or at low levels, or when an isotopically labelled sample is needed. Many synthetic procedures have been employed but those based on the reactivity of acetylene (ethyne) and its derivatives are the most common. The topic has been reviewed by Kunau (1973) and by Sprecher (1977, 1979). The Wittig reaction which is also useful in this connection and the synthesis of isotopically labelled compounds are covered in Sections 7.2 and 7.3 respectively. 

The aim of this chapter is to collect and discuss the use of phosphonates in the synthesis of biologically active or natural products in the last decade. Since in this period, innumerable syntheses of such compounds have been effected with these reagents, we have restricted our discussion to such cases where more extensive use of phosphonates in total syntheses is reported. Therefore, the synthetic approaches to bioactive products, where a single Horner-Wittig or other phosphonate reaction was use are beyond the scope of this review. Moreover, this article is not intended to provide a comprehensive coverage of the field. It highlights some of the recent developments reported in the literatme with the hope to stimulate further research in this area. 

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