Intermediate phosphinyl

We have investigated the reaction of NH phosphinous amides with diphenyl-cyclopropanone. The products were unequivocally identified as the corresponding p-phosphinyl carboxamides 27 resulting from the hydrolysis of a presumed heterocyclic intermediate (Scheme 28) These results await publication. 

Grignard reactions have been used in the preparation of l-(dialkyl-phosphinyl)- ,3-dienes, e.g. (11), which are intermediates in the synthesis of antiflame polymers. Double-resonance n.m.r. techniques have been applied to the study of the reactions between thiophosphoryl halides and Grignard reagents. For example, the reaction between methylmag-nesium iodide and t-butyldibromophosphine sulphide gave the mixed... 

Phosphinyl radicals, obtained by hydrogen abstraction from dialkyl phosphites, have been trapped with t-nitrosobutane and the resultant nitroxyl radicals examined by e.s.r, The reaction of phosphinyl radicals, e.g. (5) and (6), with olefins has been shown to occur with retention of configuration at phosphorus. " These radicals have also been postulated as intermediates in the reactions of dialkyl disulphides and diaryl disulphides with phosphinates. " From the reaction of diphenyl disulphide... 

Numerous sulfur and phosphorus peroxy compounds such as monopersulfuric acid (Caro s acid, la), monopersulfate (Oxone, Ib), ammonium monopersulfate Ic, tetra n-butyl-ammonium monopersulfate Id, peroxydisulfates 2a and 2b", tetra n-butylammonium peroxydisulfate 2c, symmetrical bissulfonyl peroxide 3 , acyl sulfonyl peroxide 4 , unsymmetrical sulfonyl peroxide 5 , sulfinyl peroxy intermediates 6a, sulfonyl peroxy intermediate 6b, sulfonimidoyl peroxy intermediate 7, bis(diphenyl phosphinyl) peroxide 8 , unsymmetrical phosphorus peroxide 9 and phosphoranyl peroxy intermediate 10" are known. Recently, many researchers have shown interest in the preparation and... 

Thermal and photochemical decomposition of 8 are well studied . When the phosphinyl oxygen is labeled with oxygen-18 as in 62, thermal decomposition of 62 results in the rearrangement product 63 without scrambling of the label. This suggests that the decomposition involves either a concerted process or an ion pair intermediate (equation 96). 

In addition to the results described, enantioselective access to 2-phosphino alcohols could be accomplished, too [71]. Starting from a borane-protected a-phosphino aldehyde hydrazone 91 as the key intermediate and available by two different approaches, the enantioselective synthesis of the desired 2-phosphino alcohols 93 could be accomplished. Thus, the electrophilic phosphinylation of aldehyde hydrazones 90 (via route I with the chlorodiphenylphosphine-borane adduct or via route II with chlorophosphines and subsequent phosphorus-boron bond formation) and the alkylation of phosphino acetaldehyde-SAMP hydrazones 92 (route III) was carried out (Scheme 1.1.26). 

Reduction of 10 with lithium aluminum hydride (LAH) in ether furnished19 an intermediate, presumably the phosphine derivative 11, which was treated with acid to effect ring enlargement, giving the 5-phosphino-D-xylopyranose derivative 14. This compound was immediately converted by air oxidation19 into the stable crystalline compounds, 5-deoxy-3-0-methyl-5-C-(phosphinyl)-D-xylopyranose (15) and the 5-C-(hydroxyphosphinyl) derivative 16 in overall yields of 15 and 3.5%, respectively, from 10. Compound 16 was obtained in 90% yield from 15 by oxidation with bromine.19 No mutarotation was observed19 for compounds 15 and 16 in water during 48 h. 

Likewise, the use of diethyl butylphosphonite in the Michaelis-Arbuzov reaction of 8 gave29 5-C-(butylphosphinyl)-D-xylopyranose 31 (50% yield) by way of intermediate 27 (R = Bu). The product was also characterized as the tri-O-acetyl derivative a single compound (m.p. 218.5-220°) was recovered,29 and structure 35, namely, 5-[(R)-butyl-phosphinyl]-/ -D-xylopyranose, could be assigned33 to this product from its n.m.r. spectrum. 

Interesting work by Lappert, Goldwhite, and co-workers (1,2) has established that phosphinyl radicals can be stabilized by means of bulky substituents such as (Me3Si)2CH. We have found that these radicals constitute a new class of ligand intermediate in character between phosphenium cations and phosphide anions. 

A two-step procedure for the oxidation of amines to hydroxylamines involves nucleophilic displacement along the peroxide bond of dibenzoyl peroxide and saponification of the intermediate O-ben-zoylhydroxylamine. Primary and secondary amines have been oxidized in this way (equation 29). Related reactions for transformation of amines to O-(arylsulfonyl)- and O-phosphinyl-hydroxylamines have been described by means of bis(arylsulfonyl) and bis(diphenylphosphinyl) peroxide, respectively 86,87... 

The reaction of COClj with (+)-l-methylheptyl methylphenyl phosphinate gave (+)-l-methyl-1-chloroheptane and methylphenyl phosphinyl chloride [816]. This indicates that the alkyl chloride is produced by an S. p displacement on a unsiphosphonium intermediate by chloride ions. 

Cobyrinic acid acts as the substrate for the first of two amidases, CbiA, which amidates the a and c acetic acid side chains (Figure 24). As with CobB, CbiA uses glutamine as its preferred amino donor and requires ATP as an energy source. Kinetic analysis has shown that the hydrolysis of glutamine and the synthesis of cobyrinic acid tf,c-diamide are uncoupled. It was also shown that the amino groups are transferred in the order of r first and then a, allowing a model to be proposed whereby phosphinylated intermediates are formed. ... 

The PH2 phosphinyl radical is formed as an intermediate in the photolysis of phosphine below, but the parent phosphinyl and phosphoranyl radicals are generally not easily obtained. They can, however, be produced by y-irradiation of phosphine trapped in a krypton matrix at 4.2 K (13.156), (2.1) and (2.2). 

The ylide (14), stabilized by both sulphonium and phosphinyl substituents, has been prepared and reacts with Michael acceptors to give phosphonocyclopropanes. The same cyclopropane (15) results from addition to both maleate and fumarate, implicating the betaine (16) as a common intermediate. 

The calculated minimum energy paths of Eqs. (5.19) and (5.20) and the intermediate structures LXIc and LXIIc expected to be formed on these paths are compatible with the stereochemical outcome of the substitution reaction associated with the inversion of the pyramidal bond configuration at tricoordinate sulfur and phosphorus centers. Such a stereochemical outcome was obtained experimentally in reactions of various sulfmyl [177] and phosphinyl [178] derivatives. 

The first D-glucopyranose derivative with phosphorus in the ring, compound (11), has been prepared via the 5-C-phosphinyl sugar (12) which was formed by addition of methyl phenylphosph-onate to a hydrazone intermediate (Scheme 3). The configuration at phosphorus, carbon-1 and carbon-5 was assigned from the Jpjj coupling constants calculated from the n.m.r. spectrum of (11), since model compounds showed a relationship between values... 

Et0)2P=0 radicals, obtained from t-BuO and (Et0)2P(H)=0, abstract halogen from alkyl halides, with competition studies being used to establish relative rates. Absolute second-order rate constants for reaction with butyl halides are 10 times slower for the phosphonyl radical compared with Et3Si. Phosphinyl-radical intermediates are implicated from ESR and P cidnp experiments when ketoximato-phosphorus(III) intermediates (formed from ketoximes and X2PCI at low temperatures) rearrange... 

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