1449-89-4Relevant academic research and scientific papers
Experimental Tests of the Stereoelectronic Effect at Phosphorus: Nucleophilic Reactivity of Phosphite Esters
Taira, Kazunari,Mock, William L.,Gorenstein, David G.
, p. 7831 - 7835 (1984)
Triethyl phosphite rapidly reacts with ethyl benzenesulfenate or diethyl peroxide to yield pentaethoxyphosphorane.In contrast, 1-methyl-4-phospha-3,5,8-trioxabicyclooctane (1) fails to react with either electrophile to yield the expected bicyclic phosphorane 5.The poor reactivity of the bicyclic phosphite 1 is due to a kinetic rather than a thermodynamic barrier because 5 is formed smoothly from an equimolar mixture of P(OEt)5 and the triol 1,1,1-tris(hydroxymethyl)ethane.This result is interpreted in terms of the stereoelectronic effect.The order of nucleophilic reactivity of trialkyl phosphites with 3-benzylidene-2,4-pentanedione is also shown to be consistent with the stereoelectronic effect.The bicyclic phosphite 1 reacted 750 times slower than the pseudoequatorial 2-methoxy ester of hexahydrobenzo-1,3,2-dioxaphosphorinane in a Michael addition reaction with 3-benzylidene-2,4-pentanedione.
EXPERIMENTAL TESTS OF THE STEREOELECTRONIC EFFECT AT PHOSPHORUS: MICHAELIS-ARBUSOV REACTIVITY OF PHOSPHITE ESTERS.
Taira, Kazunari,Gorenstein, David G.
, p. 3215 - 3222 (1984)
Whereas triethyl phosphite readily reacts with benzoyl chloride to yield the Michaelis-Arbusov product, diethyl benzoyl phosphonate, 1-methyl-4-phospha-3,5,8-trioxabicyclooctane, 1, is essentially unreactive, even at a higher temperature.The bicyclic phosphite 1 also reacts slower than the triethyl phosphite 2 in an oxidation with t-butyl hydroperoxide.These results are interpreted in terms of the stereoelectronic effect.
Reaction of α-Peroxy Lactones with C, N, P, and S Nucleophiles: Adduct Formation and Nucleophile Oxidation by Nucleophilic Attack at and Biphilic Insertion into the Peroxide Bond
Adam, Waldemar,Biancafort, Lluis
, p. 1623 - 1629 (2007/10/03)
The reactions of the α-peroxy lactones 1 with a variety of carbon, nitrogen, phosphorus, and sulfur nucleophiles yield, on SN2 attack at the more electrophilic alkoxy oxygen of the peroxide bond, diverse addition and oxygen transfer products, together with the catalytic Grob-type fragmentation. The nature of the nucleophile determines the fate of the open-chain intermediate I. Thus, protic nucleophiles such as primary and secondary amines and thiols lead to the second intermediate I′ through proton shift subsequent to the SN2 step, while nonprotic amines and sulfides, as well as diazoalkanes, lead to oxidation products or to the cycloadducts 10-15. Trivalent phosphorus nucleophiles such as phosphines and phosphites and diisopropyl sulfoxylate prefer biphilic insertion, as documented by the fact that the nucleophilicity rather than the steric demand of these reagents controls their reactivity. The labile adducts undergo a variety of transformations to the final stable products. For protic nucleophiles, the amine adducts 5 and 6 are sufficiently persistent for isolation, whereas the sulfenic esters formed by thiol addition are further oxidized to the sulfinic esters 7 and 8 or react with excess thiol to the corresponding disulfides. For aprotic nucleophiles, the dipolar intermediates I decompose into acetone and CO2 with regeneration of the nucleophile (Grob-type fragmentation), as seen for DABCO and pyridine N-oxide, or they extrude the α-lactone to afford the oxygen transfer product. The corresponding ketones, pyridine N-oxide, sulfoxides, and sulfones are obtained by this route from diazoalkanes, pyridine, sulfides and sulfoxides. Additionally, the diazoalkane intermediates I also cyclize to the cycloadducts 10-12. The thermally labile phosphorus adducts 13-15, which were observed by low-temperature NMR spectroscopy, decompose to the α-lactone and the phosphorus oxides. Analogously, diisopropyl sulfite is obtained from the sulfoxylate adduct. As for the fate of the α-lactones (the reduction products of the α-peroxy lactones), the dimethyl derivative either oligomerizes to the oligoester 2a or is trapped by methanol as the α-methoxy acid 4a, while the spiroadamantyl α-lactone decarbonylates to adamantanone.
Reaction of 2-Ethoxy-5-methyl-1,3,2-dioxaphosphorinane-5-methanol 2-Sulfide and 4-Methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-Sulfide with Sulfuryl Chloride: Mechanistic and Stereochemical Considerations
Kim, Jeong Han,Craig, Donald C.,Gallagher, Michael J.,Toia, Robert F.
, p. 2161 - 2170 (2007/10/02)
Treatment of either cis- or trans-2-ethoxy-5-methyl-1,3,2-dioxaphosphorinane-r-5-methanol 2-sulfide with SO2Cl2 yielded the cyclization product 4-methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-oxide.In contrast, treatment of 4-methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-sulfide with the same reagent gave stereospecific ring opening to trans-2-chloro-5-methyl-1,3,2-dioxaphosphorinane-r-5-methyl chloride 2-oxide.
Methanolysis of 4-Methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-Oxide and 1-Sulfide: Mechanistic and Stereochemical Considerations
Kim, Jeong Han,Gallagher, Michael J.,Toia, Robert F.
, p. 715 - 722 (2007/10/02)
Methanolysis of 4-methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-oxide and 4-methyl-2,6,7-trioxa-1-phosphabicyclooctane 1-sulfide have been studied by 31P n.m.r. spectroscopy.The trans-2-methoxy-5-methyl-1,3,2-dioxaphosphorinane-r-5-methanol 2-oxide and trans-2-methoxy-5-methyl-1,3,2-dioxaphosphorinane-r-5-methanol 2-sulfide are the initially formed products, respectively, but with time a product mixture comprising the trans- and cis-isomers and the acyclic dimethyl phosphate is formed.Methanolysis of the isolated trans-isomer, and of the isolated acyclic dimethyl phosphate under the same reaction conditions, suggests that the cis-isomer results from a recyclization reaction, rather than from the alternative ring opening of the bicyclic compound.
STEREOELECTRONIC EFFECTS IN THE HYDROLYSIS OF PHOSPHONIUM IONS FROM ACYCLIC AND BICYCLIC PHOSPHOROTHIONATES
Farschtschi, Nasser,Gorenstein, David G.,Fanni, Tahsin,Taira, Kazunari
, p. 93 - 104 (2007/10/02)
The alkaline hydrolysis of the bicyclic phosphonium ion 1-methyl-3,5,8-trioxabicyclo-octane-4-methylthiophosphonium ion 1 proceeds mainly with P-O bond cleavage as shown by hydrolysis in 18O labeled water to form the cyclic epimers cis- and trans-2-methylmercapto-2-oxo-5-hydroxymethyl-1,3,2-dioxaphosphorinane (2/3) in addition to the bicyclic phosphate, 1-methyl-4-phospha-3,5,8-trioxabicyclooctane-4-oxide, 4.The trans epimer 3 is formed after pseudorotation of the triagonal bipyramid (tbp) intermediate and is the predominant initial product.This could be explained by deprotonation of the initial neutral tbp intermediate 5 followed by fast pseudorotation to give the more stable anionic tbp 5'in which the negatively charged oxygen is placed in the equatorial position of the intermediate.In contrast, the acyclic analogue triethoxy(methylthio)phosphonium ion undergoes alkaline hydrolysis with 100percent P-S bond cleavage.It is very unusual to observe P-O bond cleavage competitive with P-S bond cleavage as we have demonstrated for the hydrolysis of the bicyclic thiophosphonium ion, 1.These results are supportive of the stereoelectronic effect hypothesis.
THIONO COMPOUNDS. 9. USE OF SPECTRA TO STUDY INTERMEDIATES IN THE OXIDATION OF THIONO PHOSPHORUS COMPOUNDS
Swinson, Joel,Field Lamar,Heimer, Norman E.,Michalska, Danuta,Muccio, Donald D.,et al.
, p. 159 - 172 (2007/10/02)
Intermediates in the oxidation by m-chloroperoxybenzoic acid (MCPBA) of 13 structurally different thiophosphoramides and phosphorothioates were studied at -25 deg C to 0 deg C using NMR, EPR, UV, IR and Raman spectra.The lifetimes of intermediates ascertained by NMR varied from a few minutes to many hours at the same temperature and were longer for thiono esters than for amides, for aryl than for alkyl constituents, and for electron-donating substituents on aryl groups than for electron-withdrawing groups.The major 31P NMR peaks for all intermediates appeared in the same region, about midway between the resonances of the P(S) starting materials and the P(O) products, indicating close structural similarly to one another for the intermediates; the range of 13-33 ppm for the major peaks indicates that the intermediates are tetracoordinate and supports phosphonium polysulfide structures for them of the type R3PSx (26, Scheme 1), or perhaps R3POSx.UV spectra also afforded support for polysulfide structures, since typical absorption develops and then disappears.Raman, 31P NMR, and UV spectra are consistent with longer-term presence of bisphosphonium species (e.g. 25, from reactions of 26; Scheme 1).EPR spectra gave no indication of homolysis. - Key words: Phosphorothioates, Raman Spectra, Infrared Spectra, Thionophosphorus, NMR Spectra, Thiophosphoramides
