1,1,1,4,5,5,5-Heptafluoro-4-(trifluoromethyl)-2,3-pentanedione,a potent reagent for the synthesis of cyclic λ5σ5 phosphoranes

1,1,1,4,5,5,5-Heptafluoro-4-(trifluoromethyl)-2,3-pentanedione reacted with λ³σ³-phosphorus compounds, PR¹R²R³ (R¹ = CF₃, R² = R³ = Me, iPr, NEt₂; R¹ = NCO, R² = R³ = OMe, OEt, R²−R³ = OCH₂CH₂O, OCMe₂CMe₂O; R¹ = OSiMe₃, R² = R³ = OEt; R¹ = NEt₂, R² = R³ = OCH₂CF₃; R¹ = R² = Et₂N, R³ = OCH₂CF₃, OCH(CF₃)₂, OCH₂Ph, OC₆F₅) to give new 1,3,2λ⁵σ⁵-dioxaphospholenes. The first λ⁵σ⁵ phosphoranes with an OCN group bonded to phosphorus were obtained. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:109–113, 1998     

1,1,3,3,3-Pentafluoro-2-pentafluorophenylpropene oxide. Precursor for novel phosphonates and ylides

1,1,3,3,3-Pentafluoro-2-pentafluorophenylpropene oxide reacted with triethyl phosphite to give the ylide C₆F₅(CF₃)C=P(OEt)₃. Hydrolysis yielded the phosphonate C₆F₅(CF₃)CHP(O)(OEt)₂, which was dehydrofluorinated using Et₃N · BF₃ to form the vinyl phosphonate C₆F₅(CF₂=)CP(O)(OEt)₂, a compound available also directly from the starting epoxide and diethyl trimethylsilyl phosphite. The vinyl phosphonate and diethyl trimethylsilyl phosphite furnished a 2:1 mixture of (Z) and (E) bisphosphonates together with fluorotrimethylsilane. Thermolylsis of the ylide gave diethyl phosphorofluoridate and 1,1-difluoro-2-pentafluorophenyl-but-1-ene. © 1997 John Wiley & Sons, Inc.     

A highly tunable family of chiral bisphospholanes for rh-catalyzed enantioselective hydrogenation reactions

A set of 16 new and closely related bisphospholane ligands have been prepared by using a highly flexible and convergent approach. Each synthesis can be performed on an industrially relevant scale. The bisphosphines differ in the nature of the bridge connecting both phospholane units. Bridges are formed by three-, four-, five- and six-membered heterocyclic or alicyclic rings. Bisphospholanes and their Rh-precatalysts have been investigated by using results of theoretical calculations (DFT) and analytic measurements ((31)P and (103)Rh NMR spectroscopy, X-ray structure analysis). The studies showed that catalysts based on ligands with maleic anhydride or maleimide bridges give constantly superior enantioselectivities in methanol as the solvent. This may account for optimised steric and electronic effects. However, by changing the solvent catalysts with other backbones can give rise to excellent results. This gives proof that simple correlations between steric and electronic properties and results in the enantioselective hydrogenation frequently claimed in literature are not general.     

Friedel-crafts acylation of benzimidazolin-2-ones with aliphatic acid chlorides

The acylation of benzimidazolin-2-one and its 5,6-disubstituted derivatives with aliphatic acid chlorides in the presence of anhydrous aluminum chloride was studied. The corresponding 5(6)-acyl-, 5-R-6-acyl-, and 5,6-dimethyl-4-acylbenzimidaz-olin-2-ones, the structures of which were confirmed by the results of elementary analysis and IR, PMR, and mass spectroscopy, were obtained. The yields of the acylation products depend on the electronic effects of the substituents in the benzene ring of the benzimidazolin-2-one and on steric factors.Translated from Khimiya Geterotsiklieheskikh Soedinenii, No. 6, pp. 808–811, June, 1984.     

Analogues of DIOP. Synthesis, reactivity, and NMR behaviour

The (4R,5R)-4,5-Bis(diphenylphosphinomethyl)-2-(-naphthoxy)-1,3,2-dioxaphospholane (1) and (4R,5R)-4,5-bis(diphenylphosphinomethyl)-2-dimethylamino-2-oxo-1,3,2-dioxaphospholane (2), analogues of the chiral bisphosphine ligand DIOP, have been synthesized. Both compounds have a second phosphorus functionality in the backbone of the chiral bisphosphine. That the reactivities of the various phosphorus atoms in 1 are different was shown for the reaction with BH₃. The complexation behaviour of 1 towards Rh^I was studied with the aid of ³¹P NMR spectroscope.     

Stereochemistry of feshurin,nevskin, and colladocin

The stereochemistry of feshurin has been suggested on the basis of passage to a substance with a known absolute configuration — conferol. It has been shown that feshurin and nevskin are isomers at the C₆-OH. The configuration of nevskin has been determined. The absolute configuration of colladocin has been established by means of a study of the influence of the orientation of the hydroxy group at C₂ in terpenoid coumarins of the samarcandin series on the chemical shifts of the C₁-CH₂OAr.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 308–311, May–June, 1979.     

2-Hydroxy-1, 1-Biphenyl- and -Binaphthyl-2′-Phosphines - Synthesis,Structure and Use in Rh-Catalyzed Carbonylation

Abstract

Dibenzofuran and dinaphthofuran are cleaved by lithium in presence of electron transfer catalysts to yield C,O-dilithium reagents. These are reacted with chloro- or alkoxyphosphines providing 2-hydroxy-1,l ‘-biphenyl-2’-phosphines and 2-hydroxy-1,‘-binaphthyl-2’-phosphines which form solvent complexes with O…H?O or P…H?O bridging bonds. The planes of the benzene rings of the biphenyl units are nearly perpen-dicular in the unit cell. Line form analysis of the temperature dependent solution NMR spectra of diastereoisomeric 2-HO-C₆H₄-C₆H₄-P (tBu)Ph revealed a barriere of rotation of Δ H= 12.87 kcal/mol. The respective 0-trimethylsilyl ethers have a higher barrier, and 2-hydroxybinaphthyl-2-phosphines dont racemize after separation by HPLC.     

Surface-integral formulation of scattering theory

We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the two-body and three-body scattering wavefunctions. This formulation is valid for both short-range and long-range Coulombic interactions. New general definitions for the potential scattering amplitude are presented. For the Coulombic potentials, the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure. New post and prior forms for the Coulomb three-body breakup amplitude are derived. This resolves the problem of the inability of the conventional scattering theory to define the post form of the breakup amplitude for charged particles. The new definitions can be written as surface-integrals convenient for practical calculations. The surface-integral representations are extended to amplitudes of direct and rearrangement scattering processes taking place in an arbitrary three-body system. General definitions for the wave operators are given that unify the currently used channel-dependent definitions.