Heterocyclic synthesis phosphorus ylides

An interesting application of a phosphorus ylide in heterocyclic synthesis is in a ring annulation. The diazopyrazole (592) when treated with various phosphorus ylides gave the 3//-pyrazolo[5,l-c][l,2,4]triazole derivatives (593) with elimination of triphenylphosphine (79TL1567). 

Heterocyclic Synthesis. - The reactions of phosphorus ylides with phenan-threne-9,10-quinone (113) have been used to prepare phenanthrene [9,10-x]-fused compounds with four, five, and six membered heterocyclic rings. (E)-4-carbethoxymethylene-l,2,3,4-tetrahydro-2-quinolones 114 have been obtained from the stereoselective reaction of 3-hydroxy-1,2,3,4-tetrahydroquinoline-2,4-diones and ethyl(triphenylphosphoranylidene)acetate. A -trifluoroacetylanilines 115 react with Ph3P=C02Et producing enamine derivatives 116 as a mixture of (E)- and (Z)-isomers. Enamines 116 are useful precursors for the synthesis of indoles and quinolones. 

In the chemistry of phosphorus-stabilized carbanions the number of publications reporting theoretical studies and those reporting mechanistic studies have increased following the reduction in these numbers last year. One of these reports includes the isolation and separate decomposition of certain oxaphosphetanes and this has allowed the first kinetic study of the second step of the Wittig reaction, albeit for a rather special system. Complex phosphonate carbanions and ylides continue to be widely used in synthesis. The number of reports of the use of the aza-Wittig and related reactions in heterocyclic synthesis remains at a high level, although many of these involve relatively minor modifications of earlier work. 

Phosphorus ylides in synthesis and transformations of heterocycles 94MI4. 

The final chapter deals with phosphorus ylides, in particular of phosphacu-mulenes, and their utilization in the synthesis of a number of heterocyclic ring systems including butenolides, tetramates, and macrolides. I want to thank all authors for their excellent presentations and their splendid cooperation. 

Alkylidenephosphoranes (a.La. phosphorus yUdes) of the general formula Ph3P=CR R (1) have been frequently used in key steps of heterocycle synthesis. Numerous papers and review articles [1-4] testify their versatility in the construction of rings with sizes ranging from three to well beyond 20 and with virtually any number, kind and distribution of heteroatoms. The Wittig alkenation of carbonyl groups is doubtless the most common, though not the only, reaction of P-ylides that has been employed in the cyclization of bifunctional precursors. The cycloaddition between acyl ylides (1 = H,... 

Gautam DR, Litinas KE, Fylaktakidou KC, Nicolaides DNJ (2003) Reactions of o-quinones with a-methyl- (or methylene) substituted phosphorus ylides. Synthesis of benzo[b]furan derivatives. Heterocycl Chem 40 399-404... 

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