Direct detection of two metaphosphoramidates in −75° the solutions by 31P NMR spectroscopy

Quin, Louis D.; Bourdieu, Catherine; Quin, G. S.

doi:10.1016/s0040-4039(00)97094-1

Cited by 16 publications

(7 citation statements)

References 7 publications

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“…On the synthetic part, high electrophilicity at the phosphorus center of the monomeric metaphosphate anion and its monoesters stimulated research directed toward development of new phosphorylating agents. Since the reactivity of metaphosphate intermediates can be modulated by Lewis bases, ,, these species (as well as their analogues) might be convenient phosphate transferring reagents, provided that they could be efficiently generated under mild conditions from easily accessible precursors.…”

Section: Resultsmentioning

confidence: 99%

“…It has been postulated on several occasions that highly electrophilic metaphosphate and its analogues should form adducts with Lewis bases, including solvent molecules possessing lone electron pairs. ,,,, Formation of such species, in which fast exchange of the coordinated solvent molecules may occur prior to the reaction with a nucleophile, was advocated as an efficient mechanism for racemization in the reactions involving metaphosphate intermediates . Consistent with these, when oxidative phosphorylation of MeOH or t -BuOH (10 equiv) with pure diastereoisomers of nucleoside H -phosphonothioate 2b was carried out in THF or MeCN as solvents, 100% epimerization at the phosphorus center was observed .…”

Section: Resultsmentioning

confidence: 99%

“…These experiments indicated that the reaction proceeding via metaphosphate-type intermediates requires fine-tuning of the reactivity of the metaphosphate adducts formed to achieve satisfactory results. Since metaphosphate adducts of type 14 and 15 were apparently not reactive enough toward nucleoside 20, we investigated once again the THF adduct of type 12, but to lower its reactivity, 48 this time we performed the oxidative thiophosphorylation of 20 at -78 °C. It was rewarding to find that under such reaction conditions dinucleoside phosphorothioate 11e was rapidly formed (ca.…”

Section: Development Of Preparative Protocols For Oxidative Phosphory...mentioning

confidence: 99%

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The Case for the Intermediacy of Monomeric Metaphosphate Analogues during Oxidation of H-Phosphonothioate, H-Phosphonodithioate, and H-Phosphonoselenoate Monoesters: Mechanistic and Synthetic Studies

2008

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Studies on the reaction of H-phosphonothioate, H-phosphonodithioate, and H-phosphonoselenoate monoesters with iodine in the presence of a base led to identification of a unique oxidation pathway, which consists of the initial oxidation of the sulfur or selenium atom in these compounds, followed by oxidative elimination of hydrogen iodide to generate the corresponding metaphosphate analogues. The intermediacy of the latter species during oxidation of the investigated H-phosphonate monoester derivatives with iodine was supported by various diagnostic experiments. The scope and limitation of these oxidative transformations for the purpose of the synthesis of nucleoside phosphorothioate, nucleoside phosphorodithioate, and nucleoside phosphoroselenoate diesters was also investigated.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Development Of Preparative Protocols For Oxidative Phosphory...mentioning

confidence: 99%

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The Case for the Intermediacy of Monomeric Metaphosphate Analogues during Oxidation of H-Phosphonothioate, H-Phosphonodithioate, and H-Phosphonoselenoate Monoesters: Mechanistic and Synthetic Studies

2008

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“…Precursors 56 of amidometaphosphates 57 were photolyzed at -75 ºC and 31 P signals at 12 and 9 were recorded (Scheme 24) [54]. On the basis of theoretical calculations the chemical shift of metaphosphate is expected in the region of 50 [55].…”

Section: Evidences For Transient Intermediatesmentioning

confidence: 99%

2-Phospha- and 2,3-Oxaphosphabicyclo[2.2.2]octenes - Synthesis and Fragmentation to Low-coordinated Species

Jankowski¹,

Huben

2006

COC

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The 2-phosphabicyclo[2.2.2]octene and 2,3-oxaphosphabicyclo[2.2.2]octene systems undergo fragmentation in inert solvents on heating, or by UV-irradiation at room or low temperature. The fragmentation is of significance because it leads to the extrusion of low-coordinated species Y-P(X)O (Y = RO, R 2 N, Aryl; X = O, S, CH 2 ), which are very effective phosphorylating agents.This review covers different aspects of the 2-phosphabicyclo[2.2.2]octene and 2,3-oxaphosphabicyclo[2.2.2]octene derivatives. The first part is focused on their synthesis and structure. The reactivity of 2,3-oxaphosphabicyclooctenes involving rearrangement and fragmentation with release of the bridging P-O unit including mechanistic studies is described in the next part. The last part of the review is dedicated to the practical aspects of the utilization these compounds as phosphorylating agents.

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“…This would represent the only instance in all of the many types of ring fragmentation photolyses we have performed where a reaction other than the desired extrusion of the P-containing bridge as a low-coordinate species has taken place to a significant extent. There is no obvious reason at this time why the P-C bond in the bicyclic esters 22-25 has some lability, while the same bond in the phosphine oxides with the same framework (16,17) It may be possible to employ a different wavelength in the photolysis that will give greater selectivity for the desired extrusion process, but we have not yet performed such experiments.…”

Section: CImentioning

confidence: 99%

Ring Fragmentation Approaches to Low-Coordinate Phosphorus Species

Quin

Jankowski

Quin

et al. 1992

ACS Symposium Series

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The photochemical fragmentation of phosphine oxides with the 2-phosphabicyclo[2.2.2]octene framework constitutes a useful method for the generation of methylene(oxo)phosphoranes, R-P(O)=CH2. The previously uncharacterized and highly reactive P-phenyl and P -methyl derivatives were prepared and trapped with alcohols as phosphinates. The fragmentation also occurred when alkoxy substituents were present on phosphorus, but significant amounts of dialkyl phosphites were formed as by-products. Some new observations on the photochemical fragmentation of the 7-phosphanorbornene system have also been made. Contrary to literature reports, this system is resistant to fragmentation and does not extrude the 2-coordinate phosphoryl species. Fragmentation with loss of the phosphorus bridge does occur readily when an alcohol is also present in the medium. The data support a mechanism in which an initial photo-promoted addition reaction of the 7-phosphanorbornene and the alcohol occurs to form a 5-coordinate species, which undergoes the fragmentation. Thermal fragmentation of the 7-phosphanorbornenes is slow, but does appear to release the 2-coordinate phosphoryl species.We have demonstrated in several recent studies (1-4) that certain unsaturated bicyclic frameworks containing phosphorus functions can be fragmented in solution to release a simple phosphorus-containing moiety. The nature of the bond breaking process leaves phosphorus in these fragments in a condition of low coordination (number of attached atoms) for the particular oxidation state concerned, and the method has proved of practical value for the synthesis of several low coordination species. As a general rule, low-coordination phosphorus species are of very high reactivity and some types cannot be directly observed or isolated even when stabilization through kinetic or thermodynamic effects is attempted. In such cases, their intermediacy in chemical processes is usually demonstrated by trapping reactions. We continue to explore applications of the ring fragmentation approach in the low-coordination chemistry of phosphorus, and in this paper we will describe the first extension of our methods to the generation of two types of the 3-coordinate methylene(oxo)-

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Direct detection of two metaphosphoramidates in −75° the solutions by 31P NMR spectroscopy

Cited by 16 publications

References 7 publications

The Case for the Intermediacy of Monomeric Metaphosphate Analogues during Oxidation of H-Phosphonothioate, H-Phosphonodithioate, and H-Phosphonoselenoate Monoesters: Mechanistic and Synthetic Studies

The Case for the Intermediacy of Monomeric Metaphosphate Analogues during Oxidation of H-Phosphonothioate, H-Phosphonodithioate, and H-Phosphonoselenoate Monoesters: Mechanistic and Synthetic Studies

2-Phospha- and 2,3-Oxaphosphabicyclo[2.2.2]octenes - Synthesis and Fragmentation to Low-coordinated Species

Ring Fragmentation Approaches to Low-Coordinate Phosphorus Species

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