Phosphorus derivatives

BtH = benzotriazole Ar1 = Ph, 4-MeC6H4, or 4-CIC6H4 Ar2 = Ph, 4-MeC6H4, 4-(N02)C6H4,1-naphthyl, 2-furyl, 2-thienyl, 2-pyridyl, or 3-pyridyl 

S-Diethylisopropoxyphosphine-gold 2,3,4,6-tetra-O-acetyl-1-thio-3-D-glucopyranoside has been prepared by a novel alkoxy-interchange reaction.  

Phosphono analogues of a- and 3-D-glucose 1-phosphate, in which the anomeric oxygen is replaced by methylene, have been synthesized from corresponding bromomethyl C-glycosides using triethyl-phosphite.  

The synthesis and reactions of novel sugar bicyclo-thiophosph-ites (14)-(16) have been reported. The bicyclophosphoramidite (17) has been obtained by cyclization of the corresponding 6-substituted D-glucofuranose 3,5-cyclophosphoramidite (18).  

2-Cyclophosphoramidites of 3,5,6-tri-O-methyl-D-glucofuranose and 3,5-di-O-methyl-D-xylofuranose have been prepared conventionally the former yielded a mixture of exo and endo isomers, whereas the latter only formed an exo product.  

Condensation of aldehydo-pentose derivatives with cyanomethyl-phosphonate esters in a Knoevenagel type reaction led to the 

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The nucleophilic reacbvity of the C-5 oxygen is well documented however, no quantitative data are available. A-2-Thiazoline-5-ones (212) react at oxygen with acetyl chloride or acetic anhydride (447. 452). benzoyl chloride (447). methyl or phenyl isocyanate (467). carbamoyl chloride (453, 467). or phosphorus derivatives (468, 428) in the presence of bases to give 213, 214, 215. or 216 (Scheme 109). Strong bases such as... 

Pentavalent phosphorus derivatives can be converted to phosphonyl halides or phosphine oxides by partial hydrolysis or by other oxygen donors. 

Phosphorus derivatives of different structures have been prepared including pyrazol-1-ylphosphines PPzs, PhPPz2 and Ph2PPz (Pz for pyrazolate anion (72CRV497,80MI40402)). By transamination with tris(dimethylamino)phosphine, pyrazoles and indazole are converted into (291) and (292), respectively (67CR(C)(265)1507). 3,5-Dimethylpyrazole reacts with amidodichlorophosphates to yield triamides (293) whereas 1-substituted pyrazolones yield amidophosphates (294) (71LA(750)39). 

All the approaches for deblocking protective groups described earlier in this book have found application in the removal of protective groups from phosphorus derivatives. Because phosphate protection and deprotection are commonly associated with compounds that contain acid-sensitive sites (e.g., glycosidic linkages and DMTr-O- groups of nucleotides), the most widely used protective groups on phosphorus are those that are deblocked by base. 

Catalytic decomposition of diazocarboxylic ester 198b with an allyl-coordinated PdCl2 yielded almost quantitatively thiopyranylidene ester 202 (82CL1843). Analogous phosphorus derivatives 204a and 204b were... 

Various phosphorus derivatives Various alcohols and adds 195, 199... 

Activating agents, such as trifluoroacetic anhydride 1,1 -carbonyldiimidazolc carbodiimides sulfonyl, tosyl, and picryl chlorides and a range of phosphorus derivatives can promote direct solution reactions between dicarboxylic acids and diols or diphenols in mild conditions. The activating agents are consumed during the reaction and, therefore, do not act as catalysts. These so-called direct polycondensation or activation polycondensation reactions proceed via the in situ transformation of one of the reactants, generally the carboxylic acid, into a more... 

The diazaphosphane or aminoiminophosphane ligands with a NPN framework are another subclass of cyclophosphazenes. These compounds with both phosphorus in oxidation state (111) [104-110] and (V) [111-112] have been employed in the synthesis of four membered heterocycles and coordination chemistry with group 13 derivatives. Several complexes of trivalent phosphorus derivatives with both aluminum halide and alkyls are known as illustrated for 48 in Scheme 21 [113-119]. The structure determination of 48 confirms the formation of a four membered metallacycle [116, 117],... 

Akiba and coworkers reported a new type of anionic hexacoordinated phosphorus derivative exemplified by compound 29 bearing a stable three-membered dioxaphosphirane ring [48]. Phosphoranide 34, generated from P-H phosphorane 35 with KH in the presence of 18-crown-6, was exposed to dioxygen to give crystalline 29 (50%). Phosphate 29 was found to be quite stable as a solid to ordinary room light as well as to the air at ambient temperature for several months (Scheme 5). 

Fig. 8 Some tricyclic neutral hexacoordinated phosphorus derivatives with P-N donations...

Since 1996, Holmes and coworkers have investigated further the formation of hexacoordinated phosphorus derivatives by virtue of sulfur donation [59-64]. 

Fig. 9 Tricyclic neutral hexacoordinated phosphorus derivatives (48a-48n) with P-S donation...

Chirality is an important part of today s chemistry and, in this respect, the pseudo-octahedral geometry of hexacoordinated phosphorus derivatives is interesting as it suffices to coordinate to the central atom three identical sym-... 

The strong Bronstedt acid nature of some hexacoordinated phosphorus derivatives, [7",H ] (Et20)4 in particular, was recently used within the context of an industrial application [36]. The conjugated acid of tris(oxalato)phosphate anion 7 was found to effectively catalyze the ring-forming reaction of trimethyl-hydroquinone 63 with isophytol 64 to give (all rac)-a-tocopherol 65 (ethylene-carbonate/heptane 1 1,100 °C, 90%, Scheme 19). This process is particularly... 

C-chiral hydroxy phosphorus derivatives, which have been described so far in the literature, are secondary alcohols. Thus, the syntheses of non-racemic compounds of this type comprise two main approaches (cf. C-chiral hydroxyalkyl sulfones. Section 2.2) asymmetric reduction of the corresponding keto derivatives and resolution of racemic hydroxyalkanephosphorus substrates. 

Compound 52 is isotypic with the analogous phosphorus derivative 35. The Sil—Asl bond length in 52 is slightly shorter (2.353(5) A) than the Si—As distance in the [2+2]-cycloadduct derived from 44a and benzophe-none (2.38 A).12... 

Sheldrick, W. S. Stereochemistry of Penta- and Hexacoordinate Phosphorus Derivatives 73, 1-48 (1978). 

F. H. Westheimer (1987) has provided a detailed survey of the multifarious ways in which phosphorus derivatives function in living systems (Table 4.7). The particular importance of phosphorus becomes clear when we remember that the daily turnover of adenosine triphosphate (ATP) in the metabolic processes of each human being amounts to several kilograms Phosphate residues bond two nucleotides or deoxynucleotides in the form of a diester, thus making possible the formation of RNA and DNA the phosphate always contains an ionic moiety, the negative charge of which stabilizes the diester towards hydrolysis and prevents transfer of these molecules across the lipid membrane. 

In recent studies, Glindemann et al. (1999, 2000) attempted to obtain definite answers to one of the basic problems of prebiotic phosphorus chemistry were there realistic enrichment mechanisms for the phosphorus derivatives required in prebiotic syntheses Only if the phosphorylating agents were present in concentrated form could successful reactions have taken place. 

The conversion of isothiocyanates to isonitriles under microwave conditions has been studied by Ley and Taylor using a polymer-supported [l,3,2]oxaphospholidine [119]. The use of 3-methyl-2-phenyl-[l,3,2]oxaphospholidine in solution is less favored [120] due to the associated toxicity and instability of the phosphorus-derived reagent, as well as the need to isolate the products from a complex reaction mixture by vacuum distillation. This drawback has been resolved by attaching the active [l,3,2]oxaphospholidine to a polymer matrix. 

The main synthetic method for obtaining boroxyalkyl phosphorus derivatives, i.e., compounds with the P—C—O—B fragment, is the transesterification of a-hydroxyalkylphosphines with boric acid esters or esteri-... 

This intramolecular interaction of heteroatoms may be distorted by introducing different substituents onto the 4,6-positions of the ring. In the case of acceptor substituents, (CC13) dioxaboraphosphorinane (97) is not alkylated at the phosphorus atom and is inert to sulfur at the same time it forms a stable complex with pyridine [Eq. (96)]. In the case of donor substituents (Aik) (93)—(94), by contrast, the corresponding sulfides have been obtained and the pyridine complex is formed only with four-coordinated phosphorus derivatives. 

Sometimes more complicated ion exchange reactions are observed, especially when the cation and the anion are able to interact with one another. Then, further transformations of tricoordinated phosphorus derivatives into ammonium 1,3,2,5-dioxaborataphosphorinanes are observed [Eq. (124)]. 

If trivalent phosphoms compounds are to be treated as electron-deficient species, then reactions of oxadiazoles with some Lewis acids should be reported here. 2-Phenyl-l,3,4-oxadiazole reacting with phosphoms trichloride in pyridine solution in the presence of triethylamine at low temperature furnished the respective dichlorophosphine and chlorophosphine, which were trapped by dimethylamine to give the corresponding amides. 2-Phenyl-l,3,4-oxadiazole also interacts over 24 h with the less reactive chlorodiphenylphosphine and dichlorophenylphosphine at room temperature to give phosphines (Scheme 14) <1999CHE1117>. These reactions of oxadiazoles resemble the behavior of 1-alkylimidazoles toward trivalent phosphorus derivatives. 

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