Alkylthio-Fluoro-and Difluoromethylphosphonates: Synthesis and Reactivity

Abstract

The mimicry of rurtive phosphate eskrs has become a0 established in the dcsign of biologically-active compounds. Fluoromethylene and difluoromclhylene-phosphonetes have becn prepared as non hydmlysable analogues of nucleosidcs or phcsphoamino- acids. We have aaemptcd to exploit n new allemalive approach using mC radical chemistry from alkylthiofluoromuhylphosphonate 1 and alkyllhiodiflwrotylphosphonate 2. We first developped a new preparation of fluorinated alkylthiophosphonak esters using elstrophilic and nuclcophilic fluorine sources. Using N-fluorobcnzencsulfonimidc 1 could be obtained in modcrate yield (40%). On rhc other hand Seleclnuor^TM allowed to obtain the difluoromthylphosphonate 2 but in relatively low yield (10%). Using nucleophilic fluorine source′ (3HF-NEt) we showed thar phosphonate 1 and 2 could be obtained selectively from chlolo- and dichloromethylphosphonate esters. By this way, diethyl alkylsulfanyl- fluoromcthylphosphonate 1 and difluoromcthylphosphonate 2 were respectively rynthetized in 63% and 54% yields.     

2,3-Diphenylphosphirenepentacarbonyltungsten Complex: Synthesis and Reactivity

Abstract

2-3-Diphenylphosphirenepentacarbonyltungsten complex 1 is prepared using the following scheme :     

Intramolecular Tetrylene Lewis Adducts: Synthesis and Reactivity

A series of benzyl(diphenylphosphino) and o‐phenyl(diphenlyphosphino) substituted germylenes and plumbylenes were synthesized by nucleophilic substitution between the respective lithium reagent and tetrylene halide. The Lewis pairs were characterized by X‐ray crystallography and NMR spectroscopy. The reactivity of the tetrylenes was investigated with respect to azide addition. In the germylene case, the germaniumimide was formed as the kinetically controlled product, which rearranges upon heating to give the phosphinimide. The stannylene and plumbylene derivatives react with adamantylazide to give the azide adducts. 1‐Pentene reacts diastereoselectively with the phosphagermirane to give a cyclic addition product. Trimethysilylacetylene shows an addition with the benzylphosphino‐substituted germylene and plumbylene to give the cycloheteropentene molecules. The addition product between phenylacetylene and the four membered Ge‐P adduct shows after addition at room temperature a 1,4‐phenylmigration to give a cyclic phosphine. Alkylnitrene insertion into a Ge?C bond of the alkyne addition product of the phosphagermirane was found in reaction with adamantylazide.     

Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity

Chiral hypervalent iodine chemistry has been steadily increasing in importance in recent years. This review catalogues enantioselective transformations triggered by chiral hypervalent iodine(III/V) reagents, in stoichiometric or catalytic quantities, highlighting the different reactivities in terms of yield and enantioselectivity. Moreover, the synthesis of the most remarkable and successful catalysts has been illustrated in detail.     

Phospha-carba-oligo-enes,Synthesis and Reactivity

Abstract

The synthesis of various mono-, di- and mphosphabutadienes, of two hiphosphapentadienes and of several mono-, di- and tetraphospha-hexadienes is being reported. Their chemistry demonstrates an astonishing relationship to the corresponding olefinic compounds.     

Synthesis and Reactivity of Aminodiphosphanes

Abstract

Synthetic routes to various aminodiphosphanes 1 are reported.     

Synthesis and Reactivity of Metallophosphanes

Abstract

Aspects of the reactivity of metallophosphanes are presented along with the synthesis and structure determinations for new aluminophosphanes.     

m‐Metallaphenol: Synthesis and Reactivity Studies

Treatment of the osmium complex [Os{CHC‐(PPh₃)CH(OH)‐η²‐C≡CH}(PPh₃)₂(NCS)₂] ( 1 ) with excess triethylamine produces the first m‐metallaphenol complex [Os{CHC(PPh₃)CHC(OH)CH}(PPh₃)₂(NCS)₂] ( 2 ). The NMR spectroscopic and structural data as well as the nucleus‐independent chemical‐shift (NICS) values suggest that osmaphenol 2 has aromatic character. The reactivity studies demonstrate that 2 can react with different isocyanates to form the annulation reaction products [Os{CHC(PPh₃)CHC(O?C?ONR)C}(PPh₃)₂(NCS)₂] (R=Ph ( 3 ), iPr ( 7 ), Bn ( 8 )) via the carbamate intermediates [Os{CHC(PPh₃)CHC(O‐C?ONHR)CH}(PPh₃)₂(NCS)₂] (R=Ph ( 4 ), iPr ( 5 ), Bn ( 6 )). In addition, the similar annulation reactions can be extended to other unsaturated compounds containing N–C multiple bonds, for example, isothiocyanates, pyridine, and sodium thiocyanate, which can produce the corresponding fused osmabenzene complexes. In contrast, the reactions of 2 with common electrophiles, such as NOBF₄, NO₂BF₄, N‐bromosuccinimide, and N‐chlorosuccinimide only led to the decomposition of the metallaphenol ring. The experimental results suggest that 2 is very electrophilic and readily reacts with nucleophiles, which is mainly due to the metal center and the strong electron‐withdrawing phosphonium group.     

1,3-Benzodiphospholes - Synthesis and Reactivity

Abstract

Methods of the preparation and the reaction behaviour of 1.3-benzodiphospholes as well as their nmr spectroscopic data are discussed     

Synthesis and Reactivity of bis-Lactamic Compounds

A preparation of bis-lactams is described from α-ketols and bis-cyanamides in the presence of sodium ethoxide at room temperature. One of these compounds leads to an unsaturated derivative by condensation with furfural, or to a saturated analogue via catalytic hydrogenation.     

The Synthesis and Reactivity of Alkylaminomethylene-Diphosphonates

Abstract

A accessible method for the synthesis of various alkylaminomethylenediphos-phonates is presented. The performed Vilsmeier reagents 2 (RCONR1R²/POCl₃) react with diethyl phosphite 1 to give the products 1 in good yield.     

Synthesis and Diels-Alder Reactivity of 2,3,5,6-Tetramethylidenenorbornane

Pd-catalyzed double carbomethoxylation of the Diels-Alder adduct of cyclo-pentadiene and maleic anhydride yielded the methyl norbornane-2,3-endo-5, 6-exo-tetracarboxylate ( 4 ) which was transformed in three steps into 2,3,5,6-tetramethyl-idenenorbornane ( 1 ). The cycloaddition of tetracyanoethylene (TCNE) to 1 giving the corresponding monoadduct 7 was 364 times faster (toluene, 25°) than the addition of TCNE to 7 yielding the bis-adduct 9 . Similar reactivity trends were observed for the additions of TCNE to the less reactive 2,3,5,6-tetramethylidene-7-oxanorbornane ( 2 ). The following second order rate constants (toluene, 25°) and activation parameters were obtained for: 1 + TCNE → 7 : k₁ = (255 + 5) 10^?4 mol^?1 · s^?1, ΔH≠ = (12.2 ± 0.5) kcal/mol, ΔS≠ = (?24.8 ± 1.6) eu.; 7 + TCNE → 9 , k₂ = (0.7 ± 0.02) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.1 ± 1.0) kcal/mol, ΔS≠ = ( ?30 ± 3.5) eu.; 2 + TCNE → 8 : k₁ = (1.5 ± 0.03) 10^?4 mol^?1 · s^?1, ΔH≠ = (14.8 ± 0.7) kcal/mol, ΔS≠ = (?26.4 ± 2.3) eu.; 8 + TCNE → 10 ; k₂ = (0.004 ± 0.0002) 10^?4 mol^?1 · s^?1, ΔH≠ = (17 ± 1.5) kcal/mol, ΔS≠ = (?30 ± 4) eu. The possible origins of the relatively large rate ratios k₁/k₂ are discussed briefly.     

Synthesis and Reactivity of New Functionalized Perfluoroalkylfluorophosphates

A new efficient synthesis of functionalized perfluoroalkyl fluorophosphates by oxidative addition of Me₂NCH₂F to the electron‐deficient phosphanes (C₂F₅)_nPF_3?n (n=0–3) is reported. The initially formed zwitterionic, hexacoordinated phosphates [(C₂F₅)_nF_5?nP(CH₂NMe₂?CH₂NMe₂)] are converted into the corresponding phosphonium salts [(Me₃PCH₂NMe₂]⁺[(C₂F₅)_nF_5?nP(CH₂NMe₂)]^? by treatment with PMe₃. In addition [(C₂F₅)₃F₂P(CH₂NMe₂?CH₂NMe₂)] can undergo a 1,3‐methyl shift from the internal to the terminal nitrogen—a structural characterization was achieved from the CF₃ analogue. Reaction of [(C₂F₅)₃F₂P(CH₂NMe?CH₂NMe₃)] and PMe₃ gave rise to the formation of the zwitterionic phosphonium phosphate [(C₂F₅)₃F₂P(CH₂NMe?CH₂PMe₃)], which was fully characterized by X‐ray diffraction analysis. Moreover, an efficient one‐pot synthesis of Cs⁺[(C₂F₅)₃F₂P(CH₂NMe₂)]^? was pursued. This salt turned out to be a useful nucleophile in several alkylation reactions.     

Synthesis and Reactivity of New Organophosphorus Compounds

Abstract

Synthesis of functionally substituted organophosphorus compounds on the basis of reactions of the tri-n-butylphosphine/carbon disulfide, tri-n-butylphosphine/phenylisothiocyanate, tris(dimethylamino)phosphine/phenylisothiocyanate adducts with a wide range of different dipolarophiles are reported. The development of application of S-Li tri-n-butylphosphonio-dithioformiate derivatives to the synthesis of new types of organophosphorus compounds are reported.     

Synthesis and Reactivity of Unsaturated Bisphosphonium Salts

Abstract

The synthesis of 1, 2 vinylene bisphosphonium salts 1 has now been enlarged to the vinylogous 1, 4-butadienylene bisphosphonium salts 2. The salts 2, a new class of unsaturated disalts, have also been prepared through a two-step isomerisation of acetylenic salts. New aspects of the reactivity of salts 1 and the comparative study of salts 2 (selective cleavage reactions of P-C bonds and reactions with nucleophiles having a mobile hydrogen) are described. This reactivity allows the preparation of new series of phosphonium salts substituted by heteroatomic groups.     

Synthesis and Reactivity of Mevinolin-Like Lactone Precursors

The synthesis of mevinolin-like lactone precursors and the evaluation of their ability in the N-alkylation of N-potassium-phthalimide are reported.     

Synthesis and Reactivity of Allylic and Propargylic Trichloromethanesulfinates

Abstract

The synthesis and rearrangement of the title compounds to sulfones are discussed. A facile isomerization of the allylic trichloromethyl sulfones to the corresponding vinyl sulfones is also described.