Michael Pabel

Facile interconversions between diastereomers of chloro-bridged palladium(II) dimers of orthometallated (±)-dimethyl[1-(1-naphthyl)ethyl]amine

Abstract The important chloro-bridged dipalladium(II) resolving agents (R,R)- and (S,S)-cis-di-μ-chlorobis[1-[1-(dimethylamino)-ethyl]-2-naphthalenyl-C,N]dipalladium, (R,R)- and (S,S)-cis-1, undergo facile rearrangements into unequal mixtures of cis and trans diastereomers upon dissolution in chloroform or dichloromethane, although concentration of the solution in each case affords in high yield the pure cis diastereomer of the dinuclear metal complex as the corresponding mono-solvate in a typical second-order asymmetric transformation. When equimolar solutions of (R,R)-cis- and (S,S)-cis-1 CH2Cl2 in dichloromethane are mixed together, however, an equilibrium is rapidly established between the cis and trans diastereomers of the (R ∗ ,R ∗ )-(±) and ( R ∗ ,S ∗ ) forms of 1 and from which solution configurationally homogeneous (R ∗ ,S ∗ )-trans- 1 · CH 2 Cl 2 crystallizes in high yield by second-order asymmetric transformation. The crystal and molecular structures of (R,R)-cis- 1 · CH 2 Cl 2 and (R ∗ ,S ∗ )-trans- 1 · CH 2 Cl 2 have been determined. The optical purities of the individual enantiomers of (R ∗ ,R ∗ )-(±)- 1 · CH 2 Cl 2 have been determined by reaction with (1R,2S,5R)-menthyldiphenylphosphine or (1S, 2S, 5R)-neomenthyldiphenylphosphine in chloroform-d1 and analysis of the 31P1H NMR spectra of the resulting solutions of the corresponding bridge-split palladium(II)-phosphine epimers.

Facile syntheses and interconversions between simple phosphiranium and phosphirenium salts

Abstract The first phosphiranium salt, 1-methyl-1-phenylphosphiranium triflate ( 1 ), has been isolated in 73% yield from the reaction between 1-phenylphosphirane and methyl triflate in benzene. The crystal and molecular structures of 1 have been determined. The phosphiranium ion in 1 undergoes ring opening with water to give (±)-ethylmethylphenylphosphine oxide, and reacts with primary alcohols to give (±)-alkoxyethylmethylphenylphosphonium ions. Treatment of 1 with dimethyl- or methylphenylacetylene in dichloromethane affords over one week the corresponding substituted phosphirenium salts in high yield. Phosphirenium salts can also be prepared in high yields by reacting a chloroalkylaryl- or chlorodiarylphosphine and an alkyne with thallium(I) triflate in dichloromethane. The crystal and molecular structures of 1,2,3-trimethyl-1-phenylphosphirenium triflate have been determined. The reaction of chloromethylphenylphosphine with thallium(I) triflate in the absence of an alkyne leads to an unstable phosphinophosphonium triflate that undergoes rapid chloride exchange and/or pyramidal inversion at phosphorus under ambient conditions, as determined by variable temperature NMR spectroscopy.

Attempted resolution of free (±)-chlorophenylisopropylphosphine

Abstract (±)-Chlorophenylisopropylphosphine has been resolved in a palladium(II) complex containing the phosphine and ortho-metalated ( R )-1-[1-(dimethylamino)ethyl]naphthalene; the configurationally homogeneous ( R , R p ) diastereomer of the complex crystallises from the reaction mixture by typical second-order asymmetric transformation in overall 82% yield. The absolute configuration of the complex was determined by X-ray crystallography. The pure ( R , R p ) diastereomer of the complex reacts quantitatively with methanol in the presence of triethylamine to give the corresponding methoxyphosphine complex with complete stereoselectivity and inversion at phosphorus. All attempts at liberating optically active chlorophosphine from the palladium complex were unsuccessful.

Synthese und reaktivität kohlenwasserstoffüberbrückter komplexe von Mangan, Rhenium, Molybdän und Wolfram

Abstract The hydrocarbon-bridged complexes M(CH 2 ) n M (M = Mn(CO) 5 : n = 5 ( 2b ), 10 ( 2c ); M = Re(CO) 5 : n = 5 ( 3b ), 10 ( 3c ); M = (η 5 -C 5 H 5 )Mo(CO) 3 : n = 5 ( 4b ), 10 ( 4c ); M = (η 5 -C 5 H 5 )W(CO) 3 : n = 10 ( 5c )) are obtained by reaction of the bistriflates Y(CH 2 ) n Y (Y = F 3 CSO 3 , n = 5 ( 1b ), 10 ( 1c )) with the carbonyl metalates [M(CO) 5 ] − (M = Mn ( 2 ), Re ( 3 )) and [(η 5 -C 5 H 5 )M(CO) 3 ] − (M = Mo ( 4 ), W ( 5 )) in diethyl ether and THF, respectively. Depending on the solvent, the reaction of 1b with 2 also affords the cyclic carbene complex 2d . The action of SO 2 and CO, respectively, on the complexes 2a - c and 4b , c results in the formation of the sulfinato-S complexes [(η 5 -C 5 H 5 )(OC) 3 MoSO 2 (CH 2 ) n O 2 SMo(CO) 3 (η 5 -C 5 H 5 )] ( n = 5 ( 4b ′), 10 ( 4c ′)) and the diacyl-bridged compounds [(OC) 5 MnC (O)(CH 2 ) n (O)CMn(CO) 5 ] ( n = 3 ( 2a ′), 10 ( 2c ′)). According to an X-ray structural analysis, the monoacyl complex [(OC) 5 MnC(O)(CH 2 ) 3 Mn(CO) 5 ] ( 2e ) crystallizes in the orthorhombic space group Cmca with Z = 4, the acyl function being disordered. 1 H NMR spectroscopic investigations indicate a hindered rotation about the C α C β -σ bond in 2b,c and 3b,c .

Synthese alkylenverbrückter Metallkomplexe nach der kationischen Alkylierung mit Alkandiylbis(trifluormethansulfonaten)

Abstract The hydrocarbon-bridged metal complexes (OC) 5 M(CH 2 ) n M(CO) 5 ( 1a,2a,2b ) (M = Mn, n = 2: ( 1a ); M = Re, n = 2: ( 2a ), n = 3: ( 2b )) are obtained by reaction in dimethyl ether of the bistriflates Y(CH 2 ) n Y (Y = F 3 CSO 2 O) with the carbonyl metalates [M(CO) 5 ] − . According to 1 H NMR spectroscopic investigations, the favoured structure of 2b in solution is the conformer with C 2 v symmetry.

Copper(I)-Facilitated Methylation and Cyclic Alkylation of 1,2-Phenylenebis(phosphine)

The phosphorus centers in [Cu{1,2-C6H4(PH2)2}2]CF3SO3 are readily methylated by methyl iodide in the presence of 4 or 8 equiv potassium tert-butoxide to give 1,2-phenylenebis (methylphosphine) or 1,2-phenylenebis(dimethylphosphine), respectively, after displacement from the metal with cyanide. Under similar conditions with 8 equiv of base, 1,4-dibromobutance and 1,5-dibromopentane react to give respectively 1,2-phenylenebis (phospholane) and 1,2-phenylenebis (phosphorinane). 1,3-Dibromopropane, however, reacts with the complex under the basic conditions to give a variety of phosphines after displacement from the metal, including (R*, R*)-(±)/(R*, S*)-2,3,4,5-tetrahydro-1H-1,5-benzodiphosphepine, (R*,S*)-2,3,4,5-tetrahydro-1,5-bis (prop-1-enyl)-1H-1,5- benzodiphosphepine, (R*,S*)-2,3,4,5-tetrahydro-1,5-bis (prop-2-enyl)-1H-1,5-benzodiphosphepine, and the putative cage and macrocyclic dimers of 1,2-phenylenebis (phosphetane). The crystal structure of anti-[Ni {(R*, S*)-2,3,4,5-tetrahydro-1,5 bis (prop-1-eny...

Das Verhalten von stereoisomeren Bistriflaten des Tetrahydrofurans gegenüber ein- und zweiwertigen Carbonylmetallaten

Abstract The reaction of trans -3,4-bis(trifluoromethylsulfonyloxymethyl)oxolane ( trans - 1 ) with the carbonyl metalates [(η 5 - C 5 H 5 )M(CO) η ] − ( n = 3, M  Mo ( a ), W ( b ); n = 2, M  Fe ( c )) and [M(CO) 5 ] − (M  Mn ( d ), Re ( e )) in diethyl ether and THF, respectively, results in the formation of the hydrocarbon bridged complexes trans - 2a – e . Depending on the solvent, the reaction of trans - 1 with [Mn(CO) 5 ] − also affords the cyclic carbene complex trans - 3d . The action of CO on the manganese compound trans - 2d yields the diacyl bridged complex trans - 4d . By reaction of a 3:2 mixture of cis - 1 and trans - 1 with Na 2 [Os(CO) 4 ] in dimethyl ether, the 3-oxa-7-osmabicyclo[3.3.0]octanes cis - 5 and trans - 5 are formed with the same ratio of isomers. The structures of trans - 2e and cis - 5 were elucidated by X-ray structural analysis. trans - 2e crystallizes in the orthorhombic space group Pbcn with Z = 8, the bridging THF-ligand having twist conformation. cis - 5 crystallizes in the monoclinic space group P 2 1 / n with Z = 4; both rings reveal an envelope conformation.

1,3-Propandiylbis(pentacarbonylmangan) nach der Bistriflatmethode

Abstract The hydrocarbon-bridged manganese complex (OC) 5 Mn(CH 2 ) 3 -Mn(CO) 5 ( 1 ) is obtained by reaction of the bistriflate TfO

Macro- and spiro-heterocycles

z.sbnd;(CH 2 ) 3 OTf (TfO = F 3 CSO 2 O) with K[Mn(CO) 5 ] in diethyl ether, Compound 1 was fully characterized by common spectroscopic methods and analytical data.

1-Methyl-1-phenylphosphiranium triflate: synthesis, structure and reactivity

Publisher Summary This chapter provides a description of phosphorus in seven-membered rings. It refers to the publication of a comprehensive review by Caminade and Majoral of phosphorus-containing macrocycles and cryptands. It also mentions two important earlier reviews by Gallagher and Quin concerning the stereochemical aspects of heterocyclic phosphorus compounds. Parent rings with one phosphorus atom involving seven, eight, and nine membered rings are included in the chapter. Among seven membered rings, monocyclic phosphepanes, monocyclic phosphepins, fused benzo and dibenzo derivatives, and bicyclic systems are discussed. In eight membered rings, the first authenticated synthesis of a phosphocane, the phosphocane oxide was reported in 1972 by Markls method of cleavage of the appropriate tetraphenylalkyldiphosphonium salt. Rings with two or more heteroatoms are elucidated in the chapter. These include cyclic quarternizations at phosphorus, cyclizations involving organophosphides and other nucleophiles, metal template syntheses, cyclic phosphonites, cyclic oxphosphoranes, cyclic phosphazene derivatives, and polyazaphosphorus macrocycles. Bicyclic systems with bridgehead phosphorus include information on bridgehead tertiary phosphines, calixarene phosphites, and phosphatrenes.