Spirophosphoranes synthesis

Bismuth heterocycles, 1, 539-561 Bismuthiol I metal complexes, 6, 565 IR spectra, 6, 552 ring structure, 6, 561 structure, 6, 557 Bismuthiol II metal complexes, 6, 565 IR spectra, 6, 552 Bisnorisopenicillin, 7, 332, 333 Bisnorpenicillin V, 7, 331 Bis( l,3,4-oxathiazol-2-ones) applications, 6, 945 Bisoxiranes synthesis, 7, 42 Bi(spiroisoxazolines) synthesis, 6, 108 Bi(spirophosphoranes) polytopal rearrangements, 1, 529 reactions, 1, 535 Bispyranones synthesis, 3, 793 a,oj-Bispyranones, alkylene-irradiation, 3, 678... 

The secondary products formed in the synthesis of spirophosphoranes from trisdimethylaminophosphine and j3-amino-alcohoIs have been identified as the betaines (29), formed from the spirophosphoranes as shown. 

Cycloaddition reactions of phosphines with diketones have continued to be exploited in the synthesis of five-coordinate spirophosphoranes. 

Spirocyclophosphazene, 21 72, 109 Spiro-phosphonium hexafluorophosphate, synthesis of, 14 87 Spirophosphorane, 21 72 Spirulina ferredoxin, amino acid sequences, 38 236... 

The synthesis of an optically active chiral phosphorane in which the optical activity is solely connected with the P atom implies, for instance, the preparation of a trigonal bipyramid or a tetragonal pyramid with five different achiral ligands which would, at least theoretically, entail the possible formation in the first case of ten or in the second case of fifteen diastereoisomers requiring separation, a formidable task even in the absence of stereomutation. The problem has nevertheless been solved using three different approaches exploiting the particular properties of spirophosphoranes, as hereafter detailed. 

Even if some of the optically active spirophosphoranes mentioned above can exist as single species in the solid state, all of them are more or less rapidly transformed, when dissolved, into binary mixtures of diastereoisomers114-129 such as 12 and T3. However, a third type of synthesis yielded pure, optically active phosphoranes not subject to change when dissolved129. This was obtained by the stereospecific synthesis of the oxazaphos-pholidine 53130 (Scheme 5) derived from the —(1R, 2S)enantiomer of ephedrine by means... 

Phosphoranes devoid of polycyclic or spiran structures but with a PH bond can still be prone to P(III) P(V) equilibria, as shown by the study of the changes in the 31P NMR spectra brought about by the thermal variations to which were submitted the monocyclic phosphoranes159 82 (Scheme 15), which are intermediates in the synthesis of the spirophosphoranes 83 and whose structure and properties provide a good explanation for the redistribution of ligands observed in this series160,161. 

Phospholans and Phospholens.—Details have appeared of the preparation and properties of homocubylphosphoranes, e.g. (24), and related compounds. An improved synthesis of (24) is as shown. A full account has been given of the dynamic n.m.r. of the spirophosphoranes (25) in which the naphthyl... 

During last year the majority of researches in this area has been focused on the synthesis and structural determination of novel hypervalent phosphorus compounds as well as on the stereochemistry of pentacoordinated chiral spirophosphoranes. In these studies, Mironov et al. obtained tricyclic pentacoordinated spirophosphoranes containing a phosphorus-carbon bond with high regio- and stereo-selectivity whereas Kawashima presented the synthetic route to perfectly anti-apicophilic carba-phosphatranes. ... 

One particularly fascinating class of pentacoordinate phosphorus compounds is the class of chiral spirophosphoranes with amino acid residues as chiral chelate ligands since they can serve as important structural features relevant to chiral phosphoryl transfer pathways. Therefore, their synthesis and stereochemistry were recently widely explored." ... 

Synthesis and structure determination of novel hypervalent spirophosphoranes... 

Enzymatic phosphoryl transfer reactions are ubiquitous in nature and play significant roles in ATP hydrolysis and protein phosphorylation processess. As previously described, pentacoordinate phosphorus species have been assumed as transient intermediates or transition states in these pathways and their structural and electronic properties are undoubtedly related to the outcome of the process. Therefore, to aid understanding of the phosphorus-catalyzed biological routes, many model pentacoordinated phosphoranes have been synthesized. While most studies have focused on aspects of apicophilicity, anti-apicophilicity or Berry pseudorotation, there have been limited investigations on the stereochemistry of pentacoordinated spirophosphoranes with a chiral phosphorus atom. In the past year, much attention has been paid to the synthesis and determination of absolute configuration of several chiral pentacoordinate spirophosphoranes derived from D- and L-aminoacids. Some significant achievements in this area will be discussed in this section. 

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