- Reactivity and diastereoselectivity in the thermal and Lewis acid- catalyzed Diels-Alder reactions of N-sulfinylphosphoramidates
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The [4 + 2] cycloaddition reactions of N-sulfinylphosphoromidates, prepared from the corresponding phosphoramidates by treatment with N- (chlorosulfinyl)imidazole, and 1,3-cyclohexadiene were found to be diastereoselective in the absence (>90:10) and presence (> 95:5) of Lewis acid. The sulfur configuration of the major adduct from the cycloaddition reaction has been established unambiguously by X-ray crystallography. The use of Lewis acids improved the diastereoselectivity and yield, as Well as shortened reaction times. Based on the intermediacy of a tin chelate, and the absence of phosphoryl secondary orbital interactions, a mechanism for the cycloaddition reactions is discussed.
- Zhang,Flann
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- Iodoform, a New Reagent in the Todd-Atherton Reaction
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An innovative and convenient application of the iodoform (1) as the reagent in the synthesis of phosphoramidates via Todd-Atherton reaction is described. The full stereoselectivity of this transformation using a 4-methyl-1,3,2-dioxaphosphinane model system was demonstrated.
- Mielniczak, Grazyna,Lopusinski, Andrzej
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- Oxidation of diethyl N-sulfinylphosphoramidates
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It is reported that the diethyl N-sulfinylphosphoramidate (1a) is oxidized with iodoso-and/or iodoxybenzene as well as with organic peroxides, to give diethyl N-sulfonylphosphoramidate (7a). The latter was generated in situ at low temperature and trapped
- Mielniczak, Grazyna,Lopusinski, Andrzej
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p. 530 - 536
(2008/12/22)
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- N-sulfonyl-and N-phosphorylbenzimidoylphosphonates
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A procedure for preparing N-sulfonyl-and N- phosphorylbenzimidoylphosphonates by oxidation of the corresponding α-(sulfonylamino)-and α-(phosphorylamino)benzylphosphonates was developed. The σ constants of imidoylphosphonate groups were evaluated by 19F NMR spectroscopy, and specific features of their electronic effects were considered. The reactions of the imidoylphosphonates obtained with O-, S-, P-, and N-nucleophiles were studied. The phosphonate-phosphoramidate rearrangement of α-aminobenzylidene-bisphosphonates was found. Nauka/Interperiodica 2006.
- Kolotilo,Sinitsa,Rassukanaya,Onys'ko
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p. 1210 - 1218
(2008/02/03)
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- Design, synthesis and activity of bisubstrate, transition-state analogues and competitive inhibitors of aspartate transcarbamylase
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Aspartate transcarbamylase initiates the de novo biosynthetic pathway for the production of the pyrimidine nucleotides, precursors of nucleic acids. This pathway is particularly active in rapidly growing cells and tissues. Thus, this enzyme has been tested as a potential target for antiproliferative drugs. In the present work, on the basis of its structural and mechanistic properties, a series of substrate analogues, including potential suicide-pseudosubstrates was synthesized and their putative inhibitory effects were tested using E. coli aspartate transcarbamylase as a model. Two of these compounds appear to be very efficient inhibitors of this enzyme.
- Grison, Claude,Coutrot, Philippe,Comoy, Corinne,Balas, Laurence,Joliez, Stephane,Lavecchia, Guido,Oliger, Patrick,Penverne, Bernadette,Serre, Valerie,Herve, Guy
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p. 333 - 344
(2007/10/03)
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- One-step transformation of ammonium dialkyl phosphoroselenoates into dialkyl phosphoramidates
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Ammonium dialkyl phosphoroselenoates are directly converted into the dialkyl phosphoramidates by iodosobenzene and iodoxybenzene. The inversion of configuration at the phosphorus atom, using model diastereoisomeric ammonium cis- and trans-2-oxo-2-seleno-4-methyl-1,3,2-dioxaphosphinan system, was observed. The mechanistic scheme of this transformation is discussed.
- Mielniczak, Grazyna,Lopusinski, Andrzej
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p. 121 - 127
(2007/10/03)
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- On the route to the N-phosphoryl sulfamic acid
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Synthesis of the previously unknown N-diethyl phosphorosulfamate 15 was accomplished by direct sulfamation of diethyl phosphoroamidate 4 with sulfur trioxide-DMF complex 14. The acid 15 was isolated in form of benzyl-16 and cyclohexylammonium 17 salts, which were found to be unstable in water solution. The other possible routes to sulfamate 15 were briefly tested.
- Mielniczak,Lopusinski
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p. 785 - 791
(2007/10/03)
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- Electrophilic Amination of C-H-Acidic Compounds with 1-Oxa-2-azaspirooctane
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The reactions of 1-oxa-2-azaspirooctane (1, 3,3-pentamethyleneoxaziridine) with malonic (e. g. 4, 35) and cyanoacetic acid derivatives (e. g. 11, 13, 20) and other C-H acids have been studied.After the introduction of a 1-hydroxycyclohexylamino group at the acidic position, five different stabilisation reactions of the intermediate 2 could be classified.The most important one is an intramolecular nucleophilic attack to a nitrile group giving disubstituted 1,4-diazaspiro decanones 2a.Their ring transformations (e. g. 2a -> 3) or the introduction of a second amino group at the same carbon atom (2a -> 3a) are further new reactions.Geminal diamino acid derivatives 3a thus obtained can be stable or rearrange to 3 (R1 = NH2) or eliminate cyclohexanone (formation of 42) and/or ammonia (formation of 41 or 43).Amination of N-cyanoacetyl-protected amino acid esters (20, NHR = amino acid unit) with 1 yields cyclic dipeptide derivatives 41. Key Words: 1-Oxa-2-azaspirooctane / C-H acids / Electrophilic amination / Diamination / Amino acid derivatives / Dehydro peptides
- Andreae, Siegfried,Schmitz, Ernst,Wulf, Jens-Peter,Schulz, Burkhard
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p. 239 - 256
(2007/10/02)
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- A Simple Test for Diffusion-Limited Reactions. Near-Diffusion-Controlled Nitrene Insertion into C-H Bonds
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A test for diffusion-controlled reactions is described.It is based on a simple experiment, wherein a reactive intermediate competes for two reagents containing a different number of reactive sites.This approach allows one to estimate rate constants of rapid reactions (i.e., kr ca. kd without absolute rate measurements.The test is applied to reaction of (diethoxyphosphoryl)nitrene with hydrocarbons in perfluorinated solvents.The photogenerated singlet nitrene undergoes efficient insertion into C-H bonds, and its reactivity is unaffected by the presence of oxygen.The insertion of the nitrene into a tertiary C-H bond is found to be near-diffusion-controlled with kobs ca. 0.3kdif = 3 * 1E9 M-1 s-1.Increased selectivity for insertion into tertiary versus primary C-H bonds is observed in perfluorohexane (9.7) as compared to a hydrocarbon solvent (5.7).This diminished reactivity of the nitrene is considered as evidence for complex formation between the singlet nitrene and a solvent molecule.The rate of the complexed-singlet to triplet intersystem crossing is estimated to be 8 * 1E8 s-1.The triplet nitrene reacts by hydrogen abstraction and is scavenged by oxygen.
- Maslak, Przemyslaw
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p. 8201 - 8207
(2007/10/02)
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- N,N-DIHALOPHOSPHORAMIDES - XVI IONIC ADDITION OF DIETHYL N,N-DIBROMOPHOSPHOROAMIDATE (DBPA) TO ALKENES AND CYCLOALKENES
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The addition of DBPA to a variety of phenylethylenes, straight-chain terminal and nonterminal alkenes as well as cycloalkenes in the presence of boron trifluoride etherate has been investigated.It was found that the reaction proceeds smoothly at -20 deg C by adding an olefin to the solution of equimolar amounts of DBPA and boron trifluoride etherate in tetrachloromethane.N-Bromoadducts (mixtures or single isomers depending upon the structure of the olefin) initially formed could be reduced in situ with sodium bisulphite solution to give the corresponding diethyl N-(β-bromoalkyl)phosphoroamidates which in turn afforded β-bromoamine hydrochlorides upon treatment with hydrogen chloride in benzene at room temperature.The regiospecificity typical for Markovnikov addition, as proven by NMR and MS evidence, was observed for unsymmetrical phenylethylenes.The addition of DBPA to (E)-1-phenylpropene, (E)-2-butene, and (Z)-2-butene was also found to proceed stereospecifically affording the corresponding anti-adducts.These results are fully compatible with an ionic addition pathway and can be rationalized by assuming the intermediate formation of an electrophilic complex between DBPA and boron trifluoride.The reaction offers a new approach to aminobromination of alkenes and cycloalkenes and makes possible an easy access to β-bromoamines, the convenient precursors of aziridines.
- Osowska-Pacewicka, K.,Zwierzak, A.
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p. 4717 - 4726
(2007/10/02)
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- Chiral Mono-, Di, and Tri-chloromethylphosphonates and Phosphonothioates: Preparation, Absolute Configuration, and the Stereochemical Course of Their Reaction with Methoxide
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Enantiomerically pure (+)-(R)-O-ethyl S-methyl dichloromethylphosphonothioate, prepared using (-)-ephedrine as a chiral template, is futher chlorinated to the trichloro analogue using BunLi-CCl4 and dechlorinated by hydrogenolysis via the monochloro analogue to the corresponding methyl-phosphonothioate of known configuration.With methoxide, the trichloro derivatives gives P-C bond cleavage with inversion and the dichloro derivatives gives P-S bond cleavages with retention of configuration.In the monochloroderivative P-S and P-O bond cleavages are competitive, P-S bond cleavage occuring with 70percent inversion.Under similar reaction conditions P-S bond cleavage occurs stereospecifically with inversion of configuration in methylphosphonothioates.Methoxide treatment of (+)-(R)-ethyl isopropyl trichloromethylphosphonate results in P-C bond cleavage with inversion while (-)-(S)-ethyl phenyl dichloromethylphosphonate loses the OPh group also with inversion.Possible reaction mechanisms are discussed.
- Hall, C. Richard,Inch, Thomas D.,Peacock, Gary,Pottage, Colin,Williams, Nancy E.
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p. 669 - 674
(2007/10/02)
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- N-Chlorophosphoramidates
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The structure of the known compound O,O-Diphenyl-N-chlorophosphoramidate has been determined by X-ray diffraction.It consists of dimers, in which the monomers are connected by N-H***O hydrogen bonds.The O,O-Diethyl-N-chlorophosphoramidate homologue can be synthesized by variuos methods.At room temperature it is part of an equilibrium mixture with O,O-Diethyl-phosphoramidate and O,O-Diethyl-N,N-dichlorophosphoramidate. - Key words: O,O-Diethyl-N-chlorophosphoramidate
- Drewelies, Kurt,Pritzkow, Hans
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p. 1402 - 1405
(2007/10/02)
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- SOLVOLYSIS OF DIPHENYL AMIDOPHOSPHATES IN AQUEOUS ALCOHOLIC MEDIA
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Influence of substituent on the reaction rate of the alkali-catalyzed solvolysis of the studied compounds set has been followed.The activation entropy has also been determined.The reaction products have been identified, and their concentration ratio has been determined.The reaction selectivity is mostly influenced by sterical effects in the substrate molecule.The results obtained agree with the SN2 mechanism.
- Kasparek, Frantisek,Mollin, Jiri
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p. 386 - 396
(2007/10/02)
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- Phosphonoureide and phosphonothioureide anthelmintics
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This invention relates to novel anthelmintic compounds containing an arylene or divalent heterocyclic ring whose free valences are satisfied by 1. a disubstituted phosphoryl ureido or thioureido group and 2. an amino group or a substituted amido or thioamido group, To compositions containing them, and to methods of using them for the treatment of intestinal parasites in mammals and birds.
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