Tricyclic phosphoranes

Spiro- and Tricyclic Phosphoranes with Six- and Higher-Membered Rings... 

Bicvclic and Tricyclic Phosphoranes The first synthesis of a series of pentaco-ordinated structures (82a-d) containing a three-membered (phosphirene) ring has been achieved by the oxidative addition of tetrachloro-o-benzoquinone... 

Pentacoordinated and Hexacoordinated Compounds 4 Bicyclic and Tricyclic Phosphoranes... 

Reaction of A, P-X, P-diphosphane 80 with 71 gave a mixture of products from which the tricyclic phosphorane 81 was isolated and its structure determined by X-ray crystallography. The coordination geometry at phosphorus is a distorted tbp with a very long equatorial P- C(CF3)2 bond of 193.2 pm. ... 

Bicvclic and Tricyclic Phosphoranes. - The reaction of phosphorocyanatidites (96ab) with alkylidene acetamide (97) proceed via the common intermediate (98) to form either (99, R= Me) by reaction with a second mole of (97) or (100) by dimerisation.30,31 An analogous dimerisation product (102) is also obtained with diphenyl carbodiimide (101)3 and the reactions of alkynylphosphonates with (101) are reported in the same paper. 

Bicvclic and Tricyclic Phosphoranes - The work of Schmutzler et al. reported in references 25 and 26, also includes the preparation and characterisation of a number of spirophosphoranes. For example the reaction of (60) with (66a-e) produced a range of spirocyclic phosphoranes (67a-e). Likewise the reaction of (66a-e) with two moles of (63) produced a series of... 

Bicyclic phosphoranes (87a-d) prepared by the reaction of (85a-d) with (86) were isolated and then characterised by m.s., elemental analysis, i.r. and multinuclear n.m.r. spectroscopy no pseudorotation was observed at ambient temperature. In a related study, tricyclic phosphoranes (89a-d) were obtained from the reaction of (88a-d) with (86). An analogous reaction between (90a-i) and (86) furnished another series of tricyclic phosphoranes (91a-i). The single crystal X-ray structure of (91a) revealed a tbp configuration about phosphorus with a 26% distortion along the Berry coordinate using P-01 as the pivot. 

Ratner, V.G. Lork, E. Pashkevich, K.I. Roschenthaler, G.V. Trifluoromethylated l,2A. -oxaphospholanes via -P-tricyclic phosphoranes from 4,4,4-trifluoro-3-hydroxy-l-phenylbutane-l-one and dichloriphosphines. J. Fluorine Chem. 1997, 85, 129-133. 

Finally, new tricyclic hexacoordinated phosphoranes with internal P-N coordination were synthesized by Swamy and coworkers by oxidative addition of cyclic phosphite precursors with quinones or with a combination of diols and (z-Pr)2NCl [57, 58]. Various ring sizes from five to eight membered were obtained showing the generality of the approach. A selection of compounds (47a-47e) is presented in Fig. 8. 

Treatment of all four diasteromers of 72 with sodium or potassium bases yielded stilbenes with high stereoselectivity (Scheme 15) <2003T255>. Two of the diastereomers gave rise to some retro-aldol products. In two cases, hexacoordinate species were identified by the upheld 31P chemical shift (5—112 ppm). It was noted that phosphoranes that ring-closed to form hexacoordinate tricyclic species were the ones that did not undergo the retro-aldol reaction to produce aldehydes. The ring closure was disfavored for intermediates with steric repulsion between trifluoromethyl and phenyl groups. 

At present, cyclic phosphoranes have been classified into four main families (Figure 4) monocyclic, bicyclic (spiro and fused), tricyclic and tetracyclic. 

Novel bicyclic (92) and tricyclic (93ab) hydrophosphoranes have been synthesized and shown to form complexes with PdCl2(COD), PdCl2(RCN)2, and Pd(allyl)Cl2 containing an open form of the phosphoranes. The Pd-catalyzed alkylation of 1,3-diphenylallyl acetate (94) with dimethyl malonate gave (95) in up to 74% ee using complexes of (92) or (93ab). " ... 

For several years, Streubel and coworkers have been exploring the chemistry of nitrilium phosphine ylides that contain low-valent organophosphorus fragments, such as complex (19) (Scheme 3). In their latest contributions to this area, they have investigated the reactions of complex (19) with phosphoranes and iminophosphoranes which have led to a number of new species containing ylidic moieties, such as the tricyclic complex (20), and 2H-l,2-azaphosphole complexes (21) and (22). Similarly, treatment of other low-valent organophosphorus complexes such as phosphinidine species (23) with stabilised phosphoranes produces new ylidic-aducts (24) and (25) (Scheme 4). ... 

A P- Al J-coupling constant for trimethylphosphine bound to the Lewis acid of Zeolite HY has been determined by Al to P INEPT methods,since coupling could not be resolved for this resonance (6= —49) in the P MAS NMR spectrum. The coupling was consistent with a five-coordinated aluminium Lewis acid/trimethyl phosphine complex, and thus a four-coordinated Lewis acid site. Bi- and tricyclic penta- and hexacoordinated-phosphoranes 25-28 have been... 

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