Diphenylphosphane Oxide Research Articles

Synthesis and Reactions of (2,2,2‐Trifluoroethyl)triphenylphosphonium Trifluoromethanesulfonate

Abstract(2,2,2‐Trifluoroethyl)triphenylphosphonium trifluoromethanesulfonate (triflate) (1) was readily synthesized in high yield from triphenylphosphane and 2,2,2‐trifluoroethyl triflate. The Wittig olefination of 1 with aromatic aldehydes bearing electron‐withdrawing groups with CsF as a base in DMF proceeded cleanly, producing the corresponding 3,3,3‐trifluoropropenylidene compounds in good yields. On the other hand, the hydrolysis of 1 in methanol containing sodium hydroxide gave (2,2‐dimethoxyvinyl)triphenylphosphonium triflate (6a) in high yield instead of the corresponding (2,2,2‐trifluoroethyl)diphenylphosphane oxide. Furthermore, reactions between 1 and secondary amines exclusively gave the novel (Z)‐(2‐amino‐2‐fluorovinyl)triphenylphosphonium triflates (10) in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

ChemInform Abstract: Synthesis and Horner—Wittig Chemistry of (Fluoromethyl)diphenylphosphane Oxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Horner−Wittig Chemistry of (Fluoromethyl)diphenylphosphane Oxide

(Fluoromethyl)diphenylphosphane oxide (1) was obtained by heating (diphenylphosphinoyl)methyl p-toluenesulfinate (2) with potassium fluoride. Compound 1 is a stable, crystalline solid, suitable for application in the Horner−Wittig reaction. The compound described in the literature under this name was found to be benzylphenylphosphinic fluoride (5). The anion of phosphane oxide 1 readily reacted with a wide range of carbonyl compounds to yield diastereomeric mixtures of α-fluoro-β-(hydroxyalkyl)phosphane oxides 7, which in most cases could be separated. The ease of phosphinate elimination to yield (E)- and (Z)-1-fluoroalkenes 8 stereoselectively was found to be strongly dependent upon conformation and substituent pattern. The route presented here avoids the use of hazardous fluorohalomethanes, which were employed in several earlier Wittig-related approaches to vinyl fluorides.

Synthesis and Horner−Wittig Chemistry of (Fluoromethyl)diphenylphosphane Oxide

(Fluoromethyl)diphenylphosphane oxide (1) was obtained by heating (diphenylphosphinoyl)methyl p-toluenesulfinate (2) with potassium fluoride. Compound 1 is a stable, crystalline solid, suitable for application in the Horner−Wittig reaction. The compound described in the literature under this name was found to be benzylphenylphosphinic fluoride (5). The anion of phosphane oxide 1 readily reacted with a wide range of carbonyl compounds to yield diastereomeric mixtures of α-fluoro-β-(hydroxyalkyl)phosphane oxides 7, which in most cases could be separated. The ease of phosphinate elimination to yield (E)- and (Z)-1-fluoroalkenes 8 stereoselectively was found to be strongly dependent upon conformation and substituent pattern. The route presented here avoids the use of hazardous fluorohalomethanes, which were employed in several earlier Wittig-related approaches to vinyl fluorides.

On the Diels−Alder Reaction of Allenes Bearing a Diphenylphosphoryl or (Trichloromethyl)sulfonyl Substituent

Diels−Alder reactions of two allenes, diphenyl(1,2-propadienyl)phosphane oxide (4) and 1,2-propadienyltrichloromethyl sulfone (7), with cyclic dienes were studied. While 4 only reacted with cyclopentadiene, to provide the endo adduct 5, the allene 7 proved to be much more reactive. Thus, the cycloaddition between 7 and N-Boc-pyrrole gave a mixture of the endo and exo adducts 9. The observed reactivities could be rationalized by semiempirical MO calculations.

Stereoselective Synthesis of (E)-Vinyl Sulfoxides by the Horner−Wittig Reaction

The Horner−Wittig reaction of sulfinylmethyl-substituted diphenylphosphane oxides 1−3 with aldehydes is reported. In a straightforward synthesis, (E)-vinyl sulfoxides 4 (R1 = Ph), 5 (R1 = Me) and 6 (R1 = pTol) were formed, mostly with high configurational selectivity and in high yields. In less selective cases, the (E)/(Z) ratio could be improved by slightly modifying the procedure. The use of (SS)-(+)-diphenyl(p-tolylsulfinylmethyl)phosphane oxide (3) allowed the synthesis of enantiomerically pure (E)-vinyl sulfoxides.

Phosphinic Acid Induced Reversal of Regioselectivity in Pd-Catalyzed Hydrophosphinylation of Alkynes with Ph2P(O)H

One drop is enough to switch from hydropalladation to phosphinylpalladation. If one drop of diphenylphosphinic acid is added for the hydrophosphinylation of alkynes with diphenylphosphane oxide, there is a reversal in regioselectivity (as shown below).

The First Examples of Enantiomerically Pure Diphosphane Dioxides—(RP,RP)‐ and (SP,SP)‐1,2‐Di‐ter‐butyl‐1,2‐diphenyldiphosphane 1,2‐Dioxides, and (RP)‐ and (SP)‐1‐tert‐Butyl‐1,2,2‐triphenyldiphosphane 1,2‐Dioxides

AbstractWhereas oxidative dimerization of each of the lithiated reagents (RP)‐ and (SP)‐tert‐butylphenylphosphane oxides 1 Li and 2 Li by means of oxygen in THF at low temperature led cleanly to meso‐1,2‐di‐tert‐butyl‐1,2‐diphenyldiphosphane dioxide (3), the respective nucleophilic substitution reactions of 1 Li and 2 Li with the (RP)‐ and (SP)‐tert‐butylphenylphosphinic bromides (4 and 6) in THF under argon led to the corresponding (SP,SP)‐ and (RP,RP)‐12‐di‐tert‐butyl‐1,2‐diphenyldiphosphane dioxides (5 and 7) in good yields, together with the meso‐diphosphane dioxide 3. The structures of 3 and 5 were established by X‐ray crystallography. Similarly, the reaction of lithiated (RP)‐phosphane oxide 1 Li with diphenylphosphinic bromide (8) or of achiral lithiated diphenylphosphane oxide 10 Li with (RP)‐tert‐butylphenylphosphinic bromide (4) provided (SP)‐tert‐butyltriphenyldiphosphane dioxide (9).

ChemInform Abstract: Boron Compounds. Part 77. Reactions of Diphenylphosphane Oxide with Organodiboranes(6). Structure of a Zwitterionic ‐POB‐ Compound.

AbstractReaction of the phosphane oxide (I) with the activated borane (II) yields the phosphinooxyborane (III).

Chemistry of 2‐Diphenylphosphoryl Ketene Thioacetals

AbstractCarbanions of diphenylphosphane oxides add to carbon disulfide to give, after alkylation, the title compounds 4. In the reaction with the allylphosphane oxide 5, exclusive γ‐attack is observed to yield dienes 6B. An exploratory study of the reactivity of 4 shows that reduction to thioacetal 7 and hydrolysis to 5‐thiocarboxylates 10 are feasible. Deprotonation of phosphane oxides having a β‐sulfur substituent reveals a high tendency to thiolate elimination to give vinyl sulfides 9, resp. 15. However, reaction of thioester 10a with benzaldehyde indicates that the compounds can be used in Wittig‐Horner olefinations. Ketene thioacetal 4e gives a 1,3 methylthio shift on treatment with acid.

Darstellung, Eigenschaften und Reaktivität von 2-, 3- und 4-Chloracyl(diphenyl)phosphanoxiden / Preparation, Properties and Reactivity of 2-, 3- and 4-Chloroacyl(diphenyl)phosphane Oxides

The highly reactive chloroacyl(diphenyl)phosphane oxides RC(O)-P(O)Ph2 (2a-d, g) [R = HCCl2 (a), CCl3 (b), CH3CHCl (c), CH3CCl2 (d), ClCH2CH2 (e), CH3CHClCH2 (f), ClCH2(CH2)2 (g)] are obtained by oxidation of the thermally labile chloroacyl(diphenyl)- phosphanes RC(O)-PPh2 (1a-d, g) with molecular oxygen in ether at low temperatures. While hydrolysis leads to a complete decomposition of 2a-d, g, the oxidation of 1a, c, e-g with oxygen in the presence of HP(O)Ph2 yields the diphosphorylated alcohols RC[P(O)Ph2]2OH (3a, c, e-g). 3e, f can be interpreted as trapping products of the not isolable oxides 2e, f. In tetrachloroethene a partial transformation of 3a into the phosphinate RC[P(O)Ph2][OP(O)Ph2]H can be observed which can be followed 31P{1H}-NMR spectroscopically. In solution the alcohols 3c, e-g decompose to give HP(O)Ph2 and the corresponding phosphane oxides 2c, e-g.

Synthese und Stabilisierung von (Benzoyl-und Pentafluorbenzoyloxy)diphenylphosphan und Vergleich mit den entsprechenden isomeren Aroyldiphenylphosphanoxiden / Synthesis and Stabilization of (Benzoyl-and Pentafluorobenzoyloxy)diphenylphosphane and Comparison with the Corresponding Isomeric Aroyldiphenylphosphane Oxides

Abstract (Benzoyloxy)-and (pentafluorobenzoyloxy)diphenylphosphanes RC(O)OPPh2 (2a, b) [R = C6H5 (a), C6F5 (b)] can be obtained by reaction of ClPPh2 (1) with NaO2CC6H5 and AgO2CCeF5, respectively [eq. (1)]. Oxidation of 2a with molecular oxygen yields (benzoyl-oxy)diphenylphosphane oxide (3a) [eq. (2)]. The complexes (OC)5CrPPh2OC(O)R (5a, b) are formed by the action of Na2OCC6H5 and AgO2CC6F5, respectively on (OC)5CrPPh2Cl (4) [eq. (3)]. The chemical and spectroscopical properties of the (aroyloxy)diphenylphosphanes (2 a, b) are compared with the corresponding aryldiphenylphosphane oxides.