Martin ligand

The formation of 27a-27e, 28, and 29 makes use of a chemistry developed by Akiba and coworkers in the 1990s for the synthesis and applications of cyclic lO-P-5 phosphoranes made of two Martin ligands. Methyl, benzyl and phenylth-... 

A range of diastereomeric spirophosphoranes were synthesized from a Martin ligand 226 and a modified Martin ligand 227, where one trifluoromethyl group is replaced by a methyl group (Scheme 31) <2002JOM441>. 

Ph4Sb0NC(CN)C(0)NH2,249 possess trigonal bipyramidal geometries.250 Reactions of the Martin ligand with triorganobismuth dihalides leading to cyclic tetraorganobismuth compounds are shown in Scheme 23.251... 

Dioxaphosphirane, a novel three membered ring of P-O-O species, has been suggested as an intermediate for singlet oxygen oxidation of trivalent phosphorus and for the decomposition of bis(phosphinic) peroxides . Akiba and coworkers reported the first isolation and structure of the dioxaphosphirane species, the phosphate 75 bearing Martin ligands and a novel three-membered ring . ... 

Oxidation of a /3-aminoalkyl selenide bearing the Martin ligand with w-chloroperbenzoic acid (MCPBA) affords the novel tetracoordinate l,2A-selenazetidines 17 (40%) and 32 (8%) as a mixture of two diastereomers, which are separated by silica gel chromatography to give stable colorless crystals. However, oxidation of the phenyl derivative yields 1,2,5-oxaselenazolidine 71 (Scheme 11) <20010L691, 2001PS259>. 

In this connection, it is interesting to note that a pentacoordinate siloxyethane 203 having a Martin ligand was isolated recently as a model for the intermediate of the Peterson... 

By further exploitation of the Martin ligand, Akiba et have extended... 

Kano, N., Xing, J.-H., Kawa, S., Kawashima, T. Cycloaddition reactions of an iminophosphorane bearing the Martin ligand with some double-bond compounds syntheses, structures and thermolyses of a 1,3,2 5-oxazaphosphetidine and a 1,3,2 5-diazaphosphetidine-4-thione. Polyhedron 2002, 21, 657-665. 

Pentacoordinate 1,2-thiaphosphetenes (103) are obtained when ylide (104), which contains a Martin ligand, is treated with aryl isothiocyanates. A series of stabilised ylides (105) has been studied as thermally latent catalysts for... 

The year has seen a considerable extension of the principles of hypervalent phosphorus chemistry into the fields of other elements notably Si, Sn, Ge and Sb and in this context the well-known Martin ligand has proved to be especially valuable. Particularly interesting contributions have been provided by Ju et al on the relative rates of reaction of pentoses and hexoses with pentacoordinate phosphorus, by Bentrude et on the mechanism of the reaction of hy-dridophosphoranes with dimethyl disulfide and by Kawashima et alP on the isolation of two carbaphosphatranes containing covalent P-C bonds. Holmes et al report on the fluxional properties of propeller shaped phosphoranes and Buono et have also demonstrated the utility of hydridophosphoranes in some highly diastereoselective reactions with isocyanates. In summary, although the number of reports was small, the year was noteworthy for some very sophisticated contributions to the field. 

Oxabismoles refer to a type of bismuth alkoxide in which the bismuth-oxygen bond is incorporated into the bismole ring system. Most known oxabismoles are benzoxabismoles as reported by Akiba et al., the unique ring system being stabilized by the Martin ligand. The general synthetic pathway to benzoxabismoles and their derivatives is shown below [930M1857]. 

The introduction of two Martin ligands onto the bismuth center enhances considerably the stability of hexacoordinated ate complexes [89TL953, 930M3297], A thermally stable spirocyclic 12-B1-6 ate complex 49 is obtained and its dynamic behavior in solution has been characterized by variable temperature F-NMR spectra. 

Oxabismole derivatives without being stabilized by the Martin ligand have been studied very little. A few examples include a cyclic bismuth carboxylate 50 which is obtained by the interaction between pentaphenylbismuth and carbon dioxide. Thermolysis of this compound leads to triphenylbismuthine, carbon dioxide and benzyne [86ZOB330]. 

Magnetism 15 Martin ligand 345-350 medicines 17-18 minerals 2-3 modification 5, 9 monoorganylbismuthines 21 mutagenicity 20... 

While the chemistry of pentacoordinated spirophosphoranes has been so far widely explored, cyclic hexacoordinate phosphorus compounds are much less studied because very often they are transient species and difficult to detect. However, an interesting example of a stable hexacoordinate phosphoranate bearing Martin ligands was recently described by Yamamoto. Another approach involved the participation of donor-acceptor nitrogen-phosphorus" and sulphur-phosphorus bonds in the formation of stable hexacoordinated compounds. 

Two examples of 10-Br-3 hypervalent bromine heterocycles (bromi-nanes) based on the Martin ligand have been reported (1980JA7382, 1986JA3803). Compounds 63 and 64 were prepared by oxidation of aryl bromides 62 with bromine trifluoride in freon solution (Scheme 8). Both brominanes are stable for an indefinite period at room temperature (mp in... 

O-Apical stereoisomers of pentacoordinated phosphoranes can be obtained by different routes, including the Kawashima s synthesis of the pentacoordinated phosphorus compound bearing a pentacoordinate silicon atom, both possessing Martin ligands in the structure or by the reaetion of 8-chloro-2-cyclohexyl-4-phenylbenzo[e]-1,2-oxaphosphinine-2-oxide with tetramethylenebis(magnesium bromide) as reported by Konovalov et al ... 

The stereochemistry of compound (4) was confirmed by X-Ray analysis and was found to be a TPB (trigonal-bypiramidal) structure with the Cl-Pl-Cl angle in the equatorial plane (136.3°) larger by 8.7° than that of P-H spirophosphorane (4) bearing Martin ligands (127.6°). This is presumably the result of steric repulsion between the bulky endo-C s groups. 

An Rh(lll) complex bearing a hypervalent phosphorus(v) ligand, Cp Rh(Cl)Rf2P (Rf= Martin ligand = o-C6H4C(CF3)20), was obtained by the reaction of Rf2P Li" with [Cp"RhCl2]2- This complex reversibly... 

Finally, the development of the chemistry of hexacoordinated phosphorus bearing transannular nitrogen compounds has continued. The isolation of a metastable geometrical isomer of a hexacoordinated dihydrophosphate containing Martin ligands has been achieved for the first time. ... 

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