Reinhard Schmutzler

IMIDAZOLYLIDENES, IMIDAZOLINYLIDENES AND IMIDAZOLIDINES

Abstract Starting from glyoxal, 1,3-diarylimidazolinium chlorides 3 were obtained in a three-step sequence via the diimines (1) and ethylene diamine dihydrochlorides (2). Reduction of 1,3-diarylimidazolinium chlorides (3) with lithium alumnium hydride furnished the 1,3-diarylimidazolidines (4) while their deprotonation with potassium hydride in thf gave access to stable carbenes (1,3-diarylimidazolin-2-ylidenes, 5). Similarly substituted imidazol-2-ylidenes are described for comparison.

C−H Insertion Reactions of Nucleophilic Carbenes

Syntheses and characterizations are described for C−H insertion products derived from 1,3-dimesityldihydroimidazol-2-ylidene (1) with acetylene, acetonitrile, methyl phenyl sulfone, and chloroform. In the reaction with acetylene, both acetylenic H-atoms are reactive so that 1 : 1 and 2 : 1 adducts can be obtained. The acetylene and methyl-phenyl-sulfone adducts are structurally characterized by means of single-crystal X-ray structure determinations. The reactions of 1,3,4,5-tetramethylimidazolidin-2-ylidene (8) with chloroform or chlorodifluoromethane are shown to yield 2-(dihaloalkyl)imidazolium salts that arise from a failure of the intermediate 2-protioimidazolium salt to capture the initially formed halocarbanion.

Calix[4]arene‐based Bis‐phosphonites, Bis‐phosphites, and Bis‐O‐acyl‐phosphites as Ligands in the Rhodium(I)‐catalyzed Hydroformylation of 1‐Octene

New calix[4]arene-based bis-phosphonites, bis-phosphites and bis-O-acylphosphites were synthesized and characterized. Treatment of these P-ligands with selected rhodium and platinum precursors led to mononuclear complexes that were satisfactorily characterized. The solid state structure of the dirhodium(I) complex 14 has been determined by X-ray diffraction. The two rhodium centres are bridged by two chloro ligands; one rhodium atom is further coordinated by calix[4]arene phosphorus atoms and the other by cyclooctadiene. The new calix[4]arene P-ligands were tested in the Rh(I) catalyzed hydroformylation of 1-octene. All Rh(I) complexes catalyzed the reaction leading to high chemoselectivity with regard to the formation of aldehydes. Yields and n/iso-selectivities depended on the reaction conditions. Average yields of 80 % and n/iso-ratios of about 1.3 to 1.5 were observed. High yields of aldehydes can be achieved using the methoxy substituted P-ligands at low Rh:ligand ratios. Auf Calix[4]arenen basierende Bis-phosphonite, Bis-phosphite und Bis-O-acyl-phosphite als Liganden in der rhodium(I)-katalysierten Hydroformylierung von 1-Octen Neue auf Calix[4]arenen basierende Bis-phosphonite, Bis-phosphite und Bis-O-acyl-phosphite wurden synthetisiert und charakterisiert. Die Umsetzung dieser Phosphorliganden mit ausgewahlten Rhodium- und Platinvorstufen fuhrte zu mononuklearen Komplexen, die vollstandig charakterisiert wurden. Durch eine Rontgenstrukturanalyse konnte die Struktur des Dirhodium( I)-Komplexes 14 im festen Zustand bestimmt werden. Die beiden Rhodiumzentren sind durch zwei Chlorliganden verbruckt, wobei das eine Rhodiumatom an die Phosphoratome des Calix[4]-arens und das andere Rhodiumatom durch das Cyclooctadien koordiniert ist. Die neuartigen phosphorhaltigen Calix[4]aren-Liganden wurden in der Rhodium(I)-katalysierten Hydroformylierung von 1-Octen getestet. Alle Rh(I)-Komplexe katalysierten die Reaktion bei hoher Chemoselektivitat, bezogen auf die Bildung von Aldehyden. Ausbeuten und n/iso-Selektivitaten waren dabei von den Reaktionsbedingungen abhangig. Durchschnittliche Ausbeuten von 80 % und n/iso-Verhaltnisse von 1.3 bis 1.5 wurden beobachtet. Hohe Ausbeuten an Aldehyden bei geringen Rhodium:Ligand-Verhaltnissen konnten durch den Einsatz von methoxysubstituierten Phosphorliganden erzielt werden.

Asymmetric synthesis of chiral N-(1-methylbenzyl)aminophosphines

The reactions of chlorophosphines 1 with (S)- or (R)-1-methylbenzylamines 2 proceed stereoselectively to give N-(1-methylbenzyl)aminophosphines 3, which were isolated as crystalline borane complexes with 100% diastereomeric purity. The absolute configuration of the new chiral compounds was established by X-ray analysis and chemical extrapolation.

Phosphorus-31 nuclear magnetic resonance studies of phosphorus—fluorine compounds

Abstract P 31 NMR chemical shifts and phosphorus—fluorine coupling constants are reported for a wide variety of phosphorus fluorides, in which the coordination number of phosphorus can have the values three, four, five, and six. The chemical shifts extend over a wide range (∼350 ppm) but are relatively constant for any particular class of compounds, and become more positive as the coordination number of phosphorus increases. The P 31 NMR spectra of the fluorophosphoranes, R n PF 5− n , confirm the previous conclusions regarding their stereochemistry.

Proton chemical shifts and 31P1H spin—spin coupling constants of some organophosphorous compounds

Abstract Proton chemical shifts δH and 31P 1H coupling constants (JP H) are reported for organophosphorus compounds containing the XCH2 P, (CH3)2N P, CH3O P and (CH3)3C P groupings, (where X = H or Cl). In particular a comparison is made of the values obtained in compounds containing phosphorus—fluorine and phosphorus—chlorine bonds. The results are discussed in relation to a simple inductive mechanism.

ADDITION VON DIMETHYLPHOSPHINOXID BZW. -SULFID AN CARBONYLVERBINDUNGEN; DARSTELLUNG VON ä-HYDROXY-PHOSPHINOXIDEN BZW. -SULFIDEN

Abstract The reaction of Me2P(:X)H [X = O: 1; X = S: 2) with fluorinated ketones produced the α-hydroxy-phosphine oxides and sulfides, 3, 4 and 6. The reaction of Me2P(:O)CH2OH with formaldehyde gave the hemiacetal 7. Compound 2 reacted with formaldehyde and chloral to the corresponding α-hydrox-yphosphine sulfides, 8 and 9. The reaction of 2 with glyoxal furnished the 2: 1 addition product 10. In the case of diacetyl and benzil, the 1 : 1 addition products 11 and 12 were formed. The reaction of 2 with acetone and cyclohexanone produced in the same fashion 13 and 14. The reaction of 2 with pivaloyl chloride was found to occur with formation of the diphosphine monosulfide 15. In the case of benzoyl chloride, the 2: 1 addition-product 16 was formed Compound 1 reacted with diketene with formation of the α-hydroxy-bis(phosphine oxide) 17. The reaction of selected a-hydroxy-phosphine oxides and sulfides with different trimethylsilylating reagents produced the corresponding trimethylsilylated compounds, 18–23.

Preparation of bis[2,4-bis(trifluoromethyl)phenyl]fluorophosphine and 2,4-bis[trifluoromethyl) phenyl-[2,6-bis(trifluoromethyl)phenyl]-fluorophosphine - two distillable monofluorophosphines. Structure of cis-dichloro-bis[2,4-bis(trifluoromethyl)phenyl)fluorophosphino]platinum(II)

Abstract Bis[2,4-bis(trifluoromethyl)phenyl]fluorophosphine, 1 , and 2,4-bis(trifluoromethyl)phenyl-[2,6-bis(trifluoromethyl)phenyl]fluorophosphine, 2 , were found amongst the products of the reaction of 1,3-bis(trifluoromethyl)benzene with n-butyllithium, followed by chlorodifluorophosphine. The mixture of 1 and 2 was a stable, distillable oily liquid, which crystallized on standing. The reaction of the mixture of 1 and 2 with dichloro-(η4-1.5-cyclooctadiene)platinum(II) led to the formation of cis-dichloro-bis(bis(2,4-bis(trifluoromethyl)phenyl)fluorophosphino)platinum(II), 3 . The products 1 , 2 and 3 were characterized by their 1H-.19F- and 31P-NMR and mass spectra. The long-range coupling constants 4J(PF) and 5J(FF) are discussed. The structure of 3 was confirmed by a single crystal X-ray investigation. 3 crystallizes in the monoclinic space group C 2/ c with cell constants a = 1331.8(3). b = 2392.5(4), c = 1263.1(2) pm, β = 93.75(2)° and Z = 4 (the complex possesses crystallographic twofold symmetry). The bond lengths Pt-P 221.7, Pt-Cl 232.6, P-F 155.9 pm all lie in the expected range for platinum fluorophosphine complexes.

Preparation and characterization of some phosphorus compounds containing the hexafluoroisopropoxy group

Abstract A series of phosphorus(V) compounds, X 2 P[OCH(CF 3 ) 2 ] 3 X = F,Cl,Br, OCH(CF 3 ) 2 ; X 2 = O, S) have been synthesized and characterized by their 31 P, 19 F, and 1 H n.m.r. spectra; by mass spectrometry; and by elemental analysis. New covalent chloroand bromo-phosphoranes were obtained by direct halogenation of the phosphite, P[OCH(CF 3 ) 2 ] 3 , whereas the first pure acyclic penta-alkoxyphosphorane was obtained from the reaction of Cl 2 P[OCH(CF 3 ) 2 ] 3 with the lithium salt, Li[OCH(CF 3 ) 2 ].

Chiral symmetric phosphoric acid esters as sources of optically active organophosphorus compounds

Abstract Chiral symmetric di- and trialkylphosphites, derivatives of (−)-borneol, (−)-menthol and (−)-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, were studied as starting reagents for the preparation of chiral organophosphorus compounds. The reaction occurs by asymmetric induction at the α-carbon atom of substituted α-alkylphosphonates. The stereoselectivity of the reaction depends on the structure of the starting compounds and the reaction conditions. The configuration of the alkylphosphonates was established by NMR spectroscopy, by transformation into α-hydroxyalkylphosphonic acids and by X-ray crystal structure analysis.