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The use of O-arylphosphoroamidites in the synthesis of nucleosides phosphates of biological interest and their P–F analogues is described. This goal is achieved by extremely smooth reaction of O-arylphosphites with fluoride anion donors. Dinucleoside phosphorofluoridites RO(R′O)PF prepared by this method can be resolved into diastereoisomeric forms. Phosphorofluoroamidites –P(F)NR2 are efficient reagents in the synthesis of corresponding esters –P(F)OR′. These P(III)–F systems are employed in a new and effective synthesis of trifluoromethylphosphonite P(III)–CF3 by reaction with (trifluoromethyl)trimethylsilane (CF3SiMe3). This reaction, catalysed by the fluoride anion, can be part of a sequential procedure that combines formation of P(III)–F compounds with their transformation into the corresponding P(III)–CF3 system. To cite this article: J. Michalski et al., C. R. Chimie 7 (2004).

The phosphine selenides, tris(dimethylamino)phosphine selenide, esters of selenophosphoric acid, and esters of selenophosphonic acid react with dihalogens and sulfuryl chloride to form halogenoselenophosphonium salts (P–SeX)+X−. The latter undergo deselenization via ligand exchange to form phosphonium salts (P–X)+X− and elemental selenium. The stability of these salts depends on the substituents at the phosphorus atom and the type of counter ion. It is likely that the phosphonium salts are in equilibrium with the corresponding phosphoranes, and this is demonstrated for esters containing an o-phenylene ligand. The structures of phosphonium salts, phosphoranes and other phosphorus compounds are supported by 31P NMR spectroscopy data and electrical conductivity. Additional evidence comes from addition reactions of halogenoselenophosphonium salts to cyclohexene.

2,4-Dinitrophenol (DNP) is a remarkably efficient activator in the reaction of P(III) amides with nucleosides to give P(III) esters in excellent yield. Typical examples of this novel procedure are presented herein. Mechanistic features of the activation were elucidated by model studies of the reaction of bis(2-cyanoethyl)diisopropylphosphoroamidite with benzyl alcohol. The importance of the initial protonation stage and formation of an intermediate P(III)-2,4-dinitrophenyl ester were clearly demonstrated by 31 P NMR spectroscopy and independent synthesis. New phosphitylating reagents containing the 2,4-dinitrophenoxy group do not require any activation.

The reaction of bis(phosphinoyl) diselenides R1R2P(O)Se–SeP(O)R1R21 with P(III) compounds has been investigated and its mechanistic features have been elucidated by variable temperature 31P NMR spectroscopy. These studies show that in most cases phosphonium intermediates 7, 13 and 10, 16 are involved. In the case when ligands on P(III) increase the stability of the five-coordinate structure, a phosphorane intermediate is observed. In the isomerization 7→10 and 13→16 the pathway of decomposition (deselenization, deoxygenation or dealkylation) to give stable end products is influenced by electronic and steric factors.

The reactions of azetidinium salts with phosphorus nucleophiles R2P(O)H have been investigated. Treatment of O-benzyl-N,N-diethyl-3-hydroxyazetidinium salt 2 with R2P(O)H in the presence of sodium hydride gave the corresponding γ-N,N-diethylamino-β-benzyloxypropylphosphonate 6a or phosphine oxide 6b. After debenzylation γ-N,N-diethylamino-β-hydroxypropylphosphonate 3a and phosphine oxide 3b were obtained. The compound 6a was converted into its sulfonate ester 8 which underwent elimination to yield 4. The structure 4 has been employed in Michael addition of R2P(O)H to form compounds 5 containing two phosphorus centers. Further compounds of type 3 have been transformed into compounds 5 by reaction with R2P(O)H in the presence of 1.1 equivalents of NaH in boiling toluene. Finally, azetidinium salts 1 have been converted into compounds 5a by reaction with two equivalents of R2P(O)H in the presence of 2.1 equivalents of NaH. Molecular mechanics with implementation of the Allinger MM2 force field and semiempirical AM1 and PM3 methods were used to investigate structures 5d and 5f.

A stereospecific synthesis of P-chiral sulfenyl chlorides 6a,b has been developed from P-chiral sulfenylamide 9a,b,c by a novel procedure employing 2Me 3 SiCl + 2EtOH as the reagent of choice. The sulfenylamides 9a,b,c were prepared either by stereospecific reaction of the P-chiral hydrogen phosphinothioate 8a with aminosulfenyl halides or separation of a mixture of diastereomeric 9a,b,c by crystallisation. P-Chiral chlorides 6a,b were allowed to react with secondary amines such as morpholine or dicyclohexyl amine. All these displacement reactions proceed with almost complete stereochemical integrity at the phosphorus atom. These abservations support a synchronous mechanism of bond breaking and bond formation during nucleophilic displacement at the dicoordinate sulfur atom. The same can be said about the reaction of sulfenamides 9a,b,c with hydrogen chloride.

The reaction of perbenzylated (±)-myo-inositol 1,2-bis- and 1,2,6-tris-phosphites with benzyl bromoacetate, followed by catalytic ( Pd C ) hydrogenolysis affords (±)-myo-inositol 1,2-bis- and 1,2,6-tris(carboxymethylphosphonate). The same procedure is used for the synthesis methyl α-D-mannopyranoside 2,3,4-tris(carboxymethylphosphonate).

An efficient procedure is described that leads to pure (SP)-O-l-menthylphenylthiophosphinate. The absolute configuration of this diastereomer was assigned by chemical correlation and confirmed by X-ray crystallography. The reaction of the isomer with phenyl azide, leading to amidate, is a new variant of the stereoselective Staudinger reaction. Addition of elemental selenium to the (SP)-thiophosphinate led to diastereomeric O-l-menthylphenylselenophosphonothioic acid, which was finally oxidized to the diastereomeric (RP1,RP2)-bis-[O-l-menthylphenylphosphonothionyl] diselenide. The diselenide structure was unambiguously confirmed by 31P NMR spectroscopy.

Stereoselective synthesis of the P-chiral thioxaphosphoranesulfenyl (dicyclohexyl)amide (l-menthyl-O)PhP(S)SN(C6H11)2 and its conversion into the P-chiral thioxaphosphoranesulfenyl chloride (l-menthyl-O)PhP(S)SCl is described. First synthesis of P-chiral thioxaphosphoranesulfenyl bromides (l-menthyl-O)PhP(S)SBr via the bromolysis of the bis-thiophosphoryl disulfide [(l-menthyl-O)PhP(S)S-)]2 is presented. Transformations of P-chiral thioxaphosphoranesulfenyl chlorides and bromides into the corresponding sulfenamides proceed with the preservation of stereochemical integrity at the chiral P-center.

The reaction of readily available dialkyltrimethylsilyl phosphites (RO)2POSiMe3 5 with sulfur dichloride leads to tetra-alkyl sym-monothio-pyrophosphates (RO)2P(O)SP(O)(OR)2 1 in high yield. The method is suitable for the synthesis of tetra t-butyl thiopyrophosphate 1d.

The reactions of bis(phosphinoyl) disulfides RR1P(O)S–S–P(O)RR11 with PIII compounds have been investigated and various mechanistic features have been elucidated by variable-temperature 31P NMR spectroscopy. These studies show that in most cases phosphonium intermediates [[graphic omitted]P(O)–S–[graphic omitted]–O–P(S)[graphic omitted]]5 and [[graphic omitted]P(S)–O–[graphic omitted] –O–P(S)[graphic omitted]]6 are involved. In cases where ligands on PIII increase the stability of the five-coordinate structures phosphorane intermediates are observed. In the isomerization 5→6, the mode of decomposition (desulfurization, deoxygenation or dealkylation) to give stable end products is influenced by electronic and steric factors. The presence of the Lewis acid BF3 influences considerably the stability of the transient species 5 and 6 and the chemoselectivity of the reaction.

A new synthetic approach to modified oligonucleotides based on N,N′-diisopropyl-di-(4-nitrophenyl)phosphoroamidite 1 is described. The procedure involves displacement of either 4-nitrophenoxy or diisopropylamino ligands. The former proceeds very fast in the presence of DBU, the latter requires activation by tetrazole. This method allows rapid and almost quantitative construction of modified nucleotides derived from thio- and selenophosphorus acids.

Internucleoside coupling by the title reagent, illustrated by synthesis of dinucleoside and trinucleoside thiophosphates and selenophosphates is accomplished by a new strategy involving the displacement of 4-nitrophenoxy group. Sodium 4-nitrophenolate formed in situ facilitates the oxidation of the intermediate pIII structures and acts as a demethylating reagent.

Synthetic oligonucleotides bearing modifications in the backbone have potentials as tools in studying and controlling biological processes.

Fluoroderivatives of phosphorus are important in the chemistry and biochemistry of both elements.1. Recently, our attention has been Focused on the synthesis of non-ionic oligodeoxynucleoside-phosphoro fluoridates and their thio− and selenoanalogues. Existing methods were, in our opinion, not suited for the synthesis of oligonucleoside− phosphorofluorides. So we devised new ones.

Reaction between oxophosphoranesulfenyl chloride 1(R = R′= EtO) and o-phenylene neopentyl phosphite 4 takes predominantly the deoxygenation course, yielding the phosphorochloridothioate 7 and the phosphate 8. Formation of minor products 5 and 6 corresponding to the desulfurization pathway, and low-temperature 31P NMR observations, are rationalized by proposing phosphoranephosphonium equilibria which are shifted towards phosphorane structures 9, 13, 11. These results supplement our earlier studies on desulfurization and deoxygenation of compound 1 with tricoordinate phosphorus compounds and add new evidence for phosphonium–phosphorane equilibria.

Trifluoroacetic anhydride reacts with organophosphorus compounds containing thiophosphoryl and selenophosphoryl groups converting them in high yield to the corresponding oxygenated systems.

The reactions of azetidinium salts with phosphorus nucleophiles R2P(O)H have been investigated. Treatment of O-benzyl-N,N-diethyl-3-hydroxyazetidinium salt 2 with R2P(O)H in the presence of sodium hydride gave the corresponding γ-N,N-diethylamino-β-benzyloxypropylphosphonate 6a or phosphine oxide 6b. After debenzylation γ-N,N-diethylamino-β-hydroxypropylphosphonate 3a and phosphine oxide 3b were obtained. The compound 6a was converted into its sulfonate ester 8 which underwent elimination to yield 4. The structure 4 has been employed in Michael addition of R2P(O)H to form compounds 5 containing two phosphorus centers. Further compounds of type 3 have been transformed into compounds 5 by reaction with R2P(O)H in the presence of 1.1 equivalents of NaH in boiling toluene. Finally, azetidinium salts 1 have been converted into compounds 5a by reaction with two equivalents of R2P(O)H in the presence of 2.1 equivalents of NaH. Molecular mechanics with implementation of the Allinger MM2 force field and semiempirical AM1 and PM3 methods were used to investigate structures 5d and 5f.

We describe the convenient synthesis of thymidine cyclic 3', 5'-phosphorofluoridate 6, which is superior to that previously reported. Our procedure is based on a sequence of reactions utilizing 3 as the key substrate. Similar sequence of reaction leads to the sulfur analogues of 6 the thymidine cyclic 3',5'-phosphorofluoridothioate 7.

The reaction of oxophosphoranesulfenyl chlorides RR'P(O)SCl 2 with P III compounds has been investigated. Its mechanistic features have been elucidated by variable-temperature 31 P NMR spectroscopy and stereochemical changes at P IV and P III phosphorus centers. These studies show that in all cases phosphonium intermediates containing the sulfur bridge>P(O)-S-P

Trimethylsilyl esters of general formula RR′POSiMe3 react in a quantitative and fully chemoselective way with sulfuryl chloride fluoride, ClSO2F, under extremely mild conditions to give phosphorofluoridates RO(R′O)P(O)F of high purity. This work provides easy access to all type of fluoridates from non-toxic starting materials. The synthetic usefulness of this method is illustrated by the synthesis of 3′- and 5′-mononucleoside phosphorofluoridates 10 and 3′,5′-dinucleoside phosphorofluoridates 11 from the corresponding nucleoside trimethylsilyl phosphites.

Activation of phosphoramidites as phosphitylating reagents in the synthesis of biophosphates and their structural analogues is of great importance. Tetrazole a customary activator can be conveniently replaced by trimethylchlorosilane (TMCS) or 2,4-dinitrophenol. Advantages of use of these reagents in the synthesis of biophosphates and their mechanism of action are discussed. Phosphites containing 4-nitrophenoxy leaving group are activated by DBU which role is revealed. Readily accessible P(III)-F structures, can be "activated" by their facile transformation into the corresponding bromides using trimethylbromosilane (TMBS). Application of phosphoramidites in synthesis of phosphates of biological interest and their activation by azolides and acids salts, including and stereochemical aspects was described in 'Topics in Current Chemistry.

Unprecedented CP systems: Me3SiX (X=Br, I) catalyses rearrangements of PIII esters R′R′′POR into the corresponding phosphoryl systems, providing a simple, mild and efficient route to a variety of structures containing PC bonds. The mechanism has been found to be fundamentally different from that of the Arbuzov–Michaelis reaction and includes three definite steps a, b and c (see scheme). Halotrimethylsilanes Me3SiX (X=Br, I) catalyse rearrangements of tricoordinate phosphorus esters R′R′′POR into the corresponding phosphoryl systems R′R′′P(O)R. This provides a simple and efficient route to a variety of structures containing phosphoruscarbon bonds, under mild conditions and with good yields. The reaction mechanism was investigated in detail by 31P NMR spectroscopy and independent synthesis of the reaction intermediates. It has been demonstrated that the primary products of this catalytic reaction are halogeno PIII structures R′R′′PX and silyl ethers ROSiMe3 and that they subsequently react to give the corresponding phosphorus silyl esters—Me3SiOPR′R′′—and alkyl halides RX. At higher temperatures these intermediates then react to form R′R′′P(O)R compounds. This paper also features the surprising observation that when esters Ph2POR and halotrimethylsilanes Me3SiX (X=Br, I) are used in 2:1 ratio, phosphonium salts Ph2R2P+X− and trimethylsilyl diphenylphosphinate—Ph2P(O)OSiMe3 —are formed as the major products. Experimental evidence indicates that the mechanisms of both reactions are fundamentally different from that of the Michaelis–Arbuzov reaction. Me3SiCl is not reactive and this paper explains why.

The mechanistic and synthetic aspects of the addition reaction of thioxophosphorane sulfenyl bromide with ethyl vinyl ether were studied in detail by NMR techniques. It has been found that the regiospecific, primary product of the reaction, 1-bromo-1-ethoxy-2S(dialkoxythiophosphoryl)ethane I, is unstable and undergoes slow decomposition to give four compounds. The formation of thiophosphoryl derivatives, vinyl ethers II and III, aldehyde IV, and the symmetrical hemiacetal anhydride V, has been considered in terms of a carbocation intermediate. By choice of the appropriate reaction conditions, the aldehyde IV can be obtained in very high yield.

First example of the PIII coupling reagent containing 4-nitrophenoxy group is described. Its usefulness is demonstrated by synthesis of dinucleoside methylphosphonate and methylthiophosphonate.

The reaction of diastereoizomeric 3′-[5′-O-(monomethoxytrityl)thymidyl]-5′-(3′-O-monomethoxytrityl)thymidine O-methyl phosphoro-thioate and 3′-[5′-O-(monomethoxytrity1) thymidy1]-5′-(3′-O-monomethoxytrityll-N6 -benzoyladenosine O-methyl phosphorothioate with sulfuryl-chloride fluoride leads to the corresponding diastereoisomeric phosphorofluoridates in highly stereoselective manner.

Trifluoroacetic anhydride reacts with organophosphorus compounds containing thiophosphoryl and selenophosphoryl groups converting them in high yield to the corresponding oxygenated systems.

Activation of phosphoramidites as phosphitylating reagents in the synthesis of biophosphates and their structural analogues is of great importance. Tetrazole a customary activator can be conveniently replaced by trimethylchlorosilane (TMCS) or 2,4-dinitrophenol. Advantages of use of these reagents in the synthesis of biophosphates and their mechanism of action are discussed. Phosphites containing 4-nitrophenoxy leaving group are activated by DBU which role is revealed. Readily accessible P(III)-F structures, can be "activated" by their facile transformation into the corresponding bromides using trimethylbromosilane (TMBS). Application of phosphoramidites in synthesis of phosphates of biological interest and their activation by azolides and acids salts, including and stereochemical aspects was described in 'Topics in Current Chemistry.

Letsinger et al. developed a phosphite method of synthesis of oligonucleotides. This method was further improved by Carruthers et al. Our present work is a useful extension of the Letsinger-Carruthers type reagents. Recently, we have been able to demonstrate that bis- (N, N-diisopropylamino)trimethylsilyloxy phosphane exhibit phosphitylating properties in the presence 1-H-tetrazole.1 Preparation of this reagent and its ability to undergo selective nucleophilic substitution at the tricoordinate phosphorus atom without affecting the silicon center under conditions which are commonly used for the phosphite triester approach has been recently described.1 In the same paper we reported remarkable chemical properties of dinucleosidetrimethyl-siloxyphosphanes. Namely their participation in Michaelis-Arbuzov type reactions under extremely mild conditions and reactions with oxalylazolides and sulfuryl chloride fluoride which are unique for these reagents.

Iodine–water oxidation of compound 1, condensation of 1 with (R)p-7 together with the reaction of the latter with trimethylsilyl azide results in the formation of stable (S)p(S)p-2.

Reaction of trifluoroacetic anhydride with chloroanhydrides of phosphorus acids R2P(O)CI results in formation of mixed anhydrides R2P(O) OCOCF3 and trifluoroacetic acid halides CF3COX (X=Cl, Br, I) in quantitative yield.

As part of our studies on the synthesis of mono- and bis-phosphonic acids, phosphine oxides and phosphines containing amino and hydroxy groups attached to tricarbon or tetracarbon chains [I], we now report our efforts to find a rational synthesis of compounds 2,3 and 4: Reagents: (a):R5R6PCH2Y, BuLi; (b): R3R4P(O)H, NaH; (c): 1. Pd/C, H2, 2 TsCl, Py; (d): 1 BuOK, BuOH, 2 R7 R2 P(Z)H, NaH.

The azolides of general formula 1 are readily available 1 and can be transformed in quantitative way by acyl fluorides or oxalyl fluoride into the corresponding P- fluorides 2. This strategy was extended towards synthesis of difluorides R-P(X)F 2 and trifluorides P(X)F 3 . The method was also successfully applied in chemistry of P-F modified nucleotides. e.g.

Organic monopyrophosphates, structural analogues of biologically important diphosphates, undergo spontaneous thiolo-thiono isomerization (1). On the basis of the detailed kinetic mechanistic studies of the isomerization of bis(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinane) 1 in 1-methylnaphtalene (MN), beiizoiiitryle or propylerie carbonate solutions the dissociative mechanism has been proposed (2): To support this mechanism we hove studied the kinetics of isomerization of 1 labelled with 35S in pyridine (Py) solutions. As To support this mechanism we hove studied the kinetics of isomerization of 1 labelled with 35S in pyridine (Py) solutions. As expected the reaction is very fast. The first-order reaction rate constant in Py at 25°C is about 107 times greater then the value obtained by extrapolation of the kinetic data for the reaction in MN. The reaction rate constant in Py solutions is almost not sensitive to triethylanunonium salt of the acid AH. This demonstrates that the dissociative step (k1...

The reaction of acyclic oxophosphoranesulphenyl chlorides, with phosphorus trichloride has been found to give thiophosphoryl chlorides, and phosphoryl oxychloride—the products of the exclusive deoxygenation of sulphenyl chloride. Optically active phosphonochloridothionates and phosphorochloridothionates in a high state of optical purity have been obtained with inversion of configuration from optically active sulphenyl chlorides and phosphorus trichloride. It has been shown, however, that cyclic oxophosphoranesulphenyl chlorides undergo simultaneous desulphurisation and deoxygenation when treated with phosphorus trichloride. Using cis- and trans-isomers of 2-chlorothio-4-methyl-1,3,2-dioxaphosphorinan-2-one it has been demonstrated that deoxygenation is accompanied by inversion, whereas desulphurisation occurs with retention at phosphorus. The mechanism of the title reaction is discussed.

Efficient, general synthesis of oxophosphoranesulphenyl chlorides ABP(O)SCl 2 based on the reaction of phosphorus trimethylsilylthionoesters ABP(S)OSiMe3 7 with chlorinating agents is described.

Unsymmetrical dithiopyrophosphates (RO)2P(S)SP(O)(RO)2 5 are formed in excellent yield and purity in reaction of dialkoxythioxaphosphoranesulfenyl chlorides 1 with trimethylsilylphosphites Me3SiOP(OR′)2 4. The full stereospecificity of this reaction has been demonstrated with an aid of diastereoisomeric cis- and trans-2-trimethylsilyloxy-4-methyl-1,3,2-dioxaphosphorinanes 9 which react with 1 with full retention of configuration at the phosphorus center. Preparation of diastereoisomeric cis- and trans-9 has been described and their configuration established.

Ziel und Ergebnis der Untersuchung ist die Synthese der relativ unbestandigen phosphororganischen Thiocyanate vom Typ R2P(X)SCN (1,12: × = O; 8: × = S) und deren Umlagerung in die thermodynamisch stabileren Isothiocyanate R2P(X)NCS (3, 24: × = O, 6: × = S). Stereochemische Untersuchungen an cyclischen diastereomeren Modellen (2617) fuhren zu dem Ergebnis, das die Umlagerung Thiocyanat Isothiocyanat durch nucleophile Partner, z. B. SCN⊖, uber ein pentakoordiniertes Zwischenprodukt oder einem entsprechenden Ubergangszustand autokatalysiert wird. Synthesis, Chemistry and Stereochemistry of Phosphororganic Thiocyanatesand IsothiocyanatesRearrangement of Thio- into Isothiocyanates The aim and result of the investigation is the synthesis of the relatively unstable organic phosphorus thiocyanates of the type R2P(X)SCN (1,12; × = O; 8: × = S) and their tranformation into the thermodynamically more stable isothiocyanates R2P(X)NCS (3, 24: × = O; 6: × = S). Stereochemical studies of cyclic diastereomeric (26 17) have shown that the conversion thiocyanate isothiocyanate is autocatalyzed by nucleophilic partners, e. g. SCN⊖, via a pentacoordinated intermediate or a corresponding transition state.

The reaction of the individual diastereoisomeric cyclic phosphorothioates 2a , 2b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.4.0) decane and 4a , 4b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.3.0) nonane series with sulphuryl chloride affords the corresponding sulphenyl chlorides 5a , 5b , 6a , 6b with retention of the configuration of the phosphorus atom. The reaction of the latter with phosphorus trichloride leads stereospecifically to the chlorophosphates 7a , 7b , 8a and 8b with full retention of configuration at phosphorus.

New applications of methods leading to anhydrides RR′P(O)OSO2R″ (1) are described: a) Reaction of acids RR′P(O)OH (2) with sulfonic imidazolides. b) Reaction of phosphorus imidazolides 4 with sulfonic acids and sulfonic anhydrides. New Methods of synthesis of anhydrides 1 have been developed. c) Reaction of phosphorus acid silyl esters RR′P(O)OSiMe3 (9) with methanesulfonic and trifluoromethanesulfonic anhydrides. d) Reaction of bis(trimethylsilyl) tert-butyl-phosphonate (10) with methanesulfonic acid leading to t BuP(O)(OSO2Me)2 (11). e) Reaction of stannyl phosphate (EtO)2P(O)OSnMe3 (15) with methanesulfonic anhydride. f) Reaction of phosphorus acid silyl esters 9 with trimethylsilyl trifluoromethanesulfonate. All methods result in high yields and can be adapted to a variety of anhydrides 1 derived from phosphoric, phosphonic, and phosphinic acids on the one hand and methanesulfonic, trifluoromethanesulfonic acids and sulfuric monoimidazolide on the other. Phosphonium intermediates have been demonstrated by low temperature FT 31P NMR spectroscopy for reaction b) and c). The anhydrides 1 are readily converted into imidazolides 4 by the reaction with N-(trimethylsilyl)imidazole which proceeds via two distinct phosphonium intermediates. With neutral and weakly basic nucleophiles, the anhydrides 1 behave as phosphorylating agents. Anhydride aus Sauren des Phosphors und des Schwefels, 2. Gemischte Anhydride von Phosphor-, Phosphon- und Phosphinsauren mit Sulfonsauren und Schwefelsaure-monoimidazolid. Neue Synthesen, neue Verbindungen und ihre Eigenschaften als Phosphorylierungsmittel Es werden neue Anwendungen der Methoden, die zu Anhydriden der Struktur RR′P(O)OSO2R″ (1) fuhren, beschrieben: a) Die Reaktion von Sauren RR′P(O)OH (2) mit Sulfonsaure-imidazoliden. b) Die Reaktion von Imidazoliden 4 von Sauren des Phosphors mit Sulfonsauren und Sulfonsaure-anhydriden. Neue Methoden zur Synthese von Anhydriden der Struktur 1 wurden entwickelt. c) Die Reaktion von Trimethylsilylestern von Sauren des Phosphors RR′P(O)OSiMe3 (9) mit Methansulfonsaure- und Trifluormethansulfonsaure-anhydriden. d) Die Reaktion von tert-Butylphosphonsaure-bis(Trimethylsilylester) (10) mit Methansulfonsaure zu tBuP(O)(OSO2Me)2 (11). e) Die Reaktion des Stannylphosphats (EtO)2P(O)OSnMe3 (15) mit Methansulfonsaure-anhydrid. f) Die Reaktion von Trimethylsilylestern 9 von Sauren des Phosphors mit Trifluormethansulfonsaure-trimethylsilylester. Alle Methoden ergeben hohe Ausbeuten und konnen an die Vielzahl der Anhydride 1 aus Phosphor-, Phosphon- und Phosphinsauren einerseits und Methansulfonsaure, Trifluormethansulfonsaure und Schwefelsaure-monoimidazolid andererseits angepast werden. Fur die Reaktionen b) und c) konnten durch Tieftemperatur-FT-31P-NMR- Spektroskopie Phosphonium-Zwischenstufen nachgewiesen werden. Die Anhydride 1 lassen sich durch Umsetzen mit N-(Trimethylsilyl)imidazol leicht in Imidazolide 4 uberfuhren; diese Reaktion lauft uber zwei verschiedene Phosphonium-Zwischenstufen. Die Anhydride 1 wirken gegenuber neutralen oder schwach basischen Nucleophilen als Phosphorylierungsmittel.

The halogenation of phenyl-and o-methoxyphenyl-o-phenylene phosphites (1b, 1c) gives at low temperature pentacoordinated dihalogenophosphoranes 4a, 4b, 5a, 5b. They are stable at room temperature with the exception of 5b. Even at-100°C 5b slowly gives a bromospirophosphorane 3b by breaking the ether linkage. The primary formed phosphorane is in an equilibrium with the phosphoniumsalt; both phosphorus compounds are proved with 31P n.m.r. spectroscopy. Die Halogenierung von Phenyl-und o-Methoxyphenyl-o-phenylenphosphit (1b, 1c) fuhrt bei tiefen Temperaturen zu pentakoordinierten Dihalogenophosphoranen 4a, 4b, 5a, 5b, die beim Erwarmen auf Raumtemperatur mit Ausnahme von 5b stabil sind. Aus 5b entsteht bereits bei-100°C langsam unter Etherspaltung ein Spirophosphoran 3b. Das primar gebildete Phosphoran liegt mit dem Phosphoniumsalz im Gleichgewicht vor; beide Phosphorverbindungen sind NMR-spektroskopisch nachweisbar.

The thiocyanation of organophosphorus compounds containing >P(X)H functional group (X = O, S) has been reinvestigated. The reaction wa shown to be highly stereospecific and proceeds with the retention of configuration at P via the thiocyanidate >P(O)SCN structure. The thiocyanidates rearrange into the isothiocyanidates >P(O)NCS with a rate of depending on structure of substrates and reaction conditions. The thiocyanation reaction of dialykl phosphite and their structural analogues offers an excellent route to the isothicyanidates >P(X)NCS and in some cases also to the thiocyanidates >P(X)SCN.

Optically active t-butylphenylphosphinothiocyanidate Bu t PhP(O)SCN 3 and t-butyl-O-methyl-phosphonothiocyanidate Bu t (MeO)P(O)SCN 7 have been prepared by condensation of the corresponding sulphenyl chlorides > P(O)SCl with trimethylsilylcyanide and isomerised into optically active t-butyl-O-methyl-phos-phonoisothiocyanidates Bu t (MeO)P(O)NCS 8 . Chirality at P in and the optical purity of the chiral phosphino (phosphono) thiocyanidates and isothiocyanidates have been determined by chemical correlations. It has been demonstrated that the thiocyanate ion and amine catalysed thiocyanidate-isothiocyanidate isomerisation > P(O)SCN → > P(O)NCS occurs stereospecifically with inversion of configuration at the P center. This result can be rationalized by postulation of a phosphorane intermediate, formed by nucleophilic attack of the SCN - anion on phosphorus, in which thiocyanate and isothiocyanate groups occupy apical positions. In connection with these studies a number of novel optically active phosphorylated derivatives of carbonic acid, > P(O)NHCSNHR, > P(O)NCCl 2 , > P(O)NCO and > P(O)NHCOOBu t , have also been synthesised.

The reaction of a trialkyl phosphite with trimethylsilyl iodide, which leads to O -trimethylsilyl esters of alkylphosphonic acid, has been shown to involve several steps, all of which are defined. The first step is the formation of the iodophosphite, involving a four centre mechanism in which P III plays the role of electrophile. This is in contrast to the analogous reaction of phosphates with alkyl halides (the Arbuzov reaction) which begins with nucleophilic attack of the phosphorus.

The reaction of triorganosilylsulfenyl halides R3SiSX (R  Ph, Et; X  Cl, Br) with carboncarbon double bonds, trialkyl phosphites, and organometallic reagents have been studied. With the first two nucleophiles the course of the reactions differed from that with organosulfenyl chlorides because of nucleophilic attack of halide ion on silyl group.

We report the synthesis of the first optically active silyl esters of phosphorus hewing too centres of chirality : one on silicon and the other on phosphorus. Compounds we obtained of general formula : t-BuPhP(X)YSiαNpPhMe X,Y=0,0( 1 ): S, ( 2 ); Se, 0(3); S, 3(4); doublet, 0( 5 ) including 1 and 3 with optical activity located on Si, 2 and 5 with the activity on Si or P and on both these centras, 4 only racemic. Absolute configurations are determined. 31P and-29Si NMR spectra of these models and their trimethylsilyl analogues are reported. The triorganosilyl group is always preferentially bound to phosphorus through oxygen atom. Surprisingly, diastereotopio NMR chemical shifts exclude the fast 1,3 migration in esters 1 and 4 . 29Si NMR spectra correspond to a tetracoordinate silicon atom.

Catalytic activities of R(+) and racemic t-butylphenylphosphinothioic acids on the mutarotation of 2,3,4,6 tetramethyl-d-glucose are studied in benzene.