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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 113-124 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrogen abstraction of radical intermediates yielded by radical addition to the methylene compound 6, shows excellent facial selectivity. Conformational analyses of the radical intermediates were carried out by quantum chemical calculations and explain these results. The chiral radicals 7 and 8, yielded from the chiral bromides 3 and 4, lead with ethyl acrylate to the adducts 28 and 29 with more 96% de. The adduct 28 was converted to the optically active γ-valerolactone 30. The structures of the bromides 3, 4 and 31 as well as the radical adducts 19a, 24 and 25 have been verified by X-ray diffraction analysis.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-6539
    Keywords: heterocycles ; insertion reactions ; phosphaalkynes ; phosphorus ylides ; triphosphetenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hitherto unknown 1,2,3-triphosphetenes RC=P—PCF3—PCF3 (3a-d) are formed as main products in reactions of phosphaalkynes R—C≡P [R = iPr2N (1a), tBu (1b), Me2EtC (1c), 1-methylcyclohexyl (1d)] with the cyclotetraphosphane (PCF3)4 (2). According to NMR results the CF3 groups in 3a-d have a trans disposition; an X-ray diffraction study of 3a confirms this structure. The P—P bond lengths in 3a are equal [2.201 (2) and 2.204 (2) Å] and correspond to single bonds. A considerable shortening is observed for the sp2-C-N bond (1.336 Å) which, together with the elongation of the P=C bond (1.746 Å), indicates effective π donation of the lone pair on nitrogen. Surprisingly, 3a can be prepared in quantitative yields by reaction of the PP ylide Me3P=PCF3 (6) with 1 a (molar ratio: 2:1). In contrast, the corresponding reactions of 6 with the alkyl-substituted phosphaalkynes 1b-d lead to the novel phosphorus ylides Me3P=C(R)—P—PCF3—PCF3PCF3 [R = tBu (10a), Me2EtC (10b), 1-methylcyclohexyl (10c)] in good yields. In their molecular groundstate structures, determined by X-ray diffraction, the lone pair on the phosphano P atom prefers the syn position with respect to the ylidic P=C bond. An unusual lengthening of the sp2-C-C bond [1.553 (4) (10a), 1.543 (6) (10b), 1.551 (4) Å (10c)] to values typical for sp3-C/sp3-C distances is observed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0044-2313
    Keywords: P—Donor/Sn—Acceptor Ligands ; Pentacarbonyl Chromium Complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alternative Ligands. XXXIV. Synthesis and Ligating Properties of P-Donor/Sn-Acceptor LigandsDonor/acceptor ligands of the type Me2PCH(R)OSnMe3 [R = H(5), Me (6), Ph (7)] have been prepared by reaction of Me3SnCl with HOCH(R)PMe2 and insertion of RCHO into the SnP bond of the stannylphosphane Me3SnPMe2, respectively. The new ligands, including the ethylen-bridged analogue Me2PCH2CH2SnMe3 (1), were used for the synthesis of the pentacarbonyl chromium complexes Cr(CO)5Me2PCH2CH2SnMe3 (11) and Cr(CO)5Me2PCH(R)OSnMe3 [R = H (12), Me (13), Ph (14)]. In addition, different routes were investigated to prepare the ligand 5-7 in the coordination sphere of the Cr(CO)5-fragment. For this purpose the ligands Me2PCH(R)OH [R = H (5′), Me (6′), Ph (7′)] and the complexes Cr(CO)5Me2PCH(R)OH [R = H (15), Me (16), Ph (17)], Cr(CO)5Me2PSnMe3 (18) and Cr(CO)5PMe2H (19) were prepared. Suitable pathways were found in the two-step process of 15-17 with nBuLi to give Cr(CO)5Me2PCH(R)OLi, followed by reaction with Me3SnCl, and the condensation of 15-17 with Me3SnCl using NEt3 as base. Besides ligands 5-7 were transformed to the corresponding phosphane sulfides Me2P(S)CH(R)OSnMe3 [R = H (8), Me (9), Ph (10)] by reaction with sulfur. Analytical (C, H) and spectroscopic investigations (NMR, IR, MS,Mößbauer), in addition to an X—ray diffraction study of 7, were performed to characterize the new compounds and to deduce information on structure and bonding.
    Notes: Donor/Akzeptor-Liganden des Typs Me2PCH(R)OSnMe3 [R = H (5), Me (6), Ph (7)] wurden durch Umsetzung von Me3SnCl mit HOCH2PMe2 bzw. durch Insertion von RCHO in die SnP-Bindung des Stannylphosphans Me3SnPMe2 dargestellt. Die neuen Liganden wurden unter Einbeziehung des ethylenverbrückten Vertreters Me3SnCH2CH2PMe2 (1) zur Synthese der Chrompentacarbonylkomplexe Cr(CO)5Me2PCH2CH2SnMe3 (11) und Cr(CO)5Me2PCH(R)OSnMe3 [R = H (12), Me (13), Ph (14)] genutzt. Zusätzlich wurden unterschiedliche Wege zur Darstellung der Liganden 5-7 in der Koordinationssphäre des Cr(CO)5-Fragments untersucht und dafür die Liganden Me2PCH(R)OH [R = H (5′), Me (6′), Ph (7′)] und die Komplexe Cr(CO)5Me2PCH(R)OH [R = H (15), Me (16), Ph (17)], Cr(CO)5Me2PSnMe3 (18) und Cr(CO)5PMe2H (19) dargestellt. Als geeignet erwiesen sich die zweistufige Umsetzung von 15-17 mit nBuLi zu Cr(CO)5Me2PCH(R)OLi, gefolgt von der Reaktion mit Me3SnCl, und die Kondensation von 15-17 mit Me3SnCl unter Verwendung von NEt3 als Hilfsbase. Die Liganden 5-7 werden schließlich noch mit Schwefel zu den Phosphansulfiden Me2P(S)CH(R)OSnMe3 [R = H (8), Me (9), Ph (10)] umgesetzt. Zur Charakterisierung und zur Absicherung der Bindungsbeschreibung dienen analytische (C, H) und spektroskopische Untersuchungen (NMR, IR, MS, Mößbauer) sowie für 7 eine Röntgenbeugungsanalyse an Einkristallen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of di(isopropyl)aminophosphaethyne 1 with iodomethane or the methyl ester of trifluormethylsulfonic acid (methyl triflate) yields the ionic 1λ3, 3λ3-diphosphetene derivatives + X- (2a: X = I; 2b: X = CF3SO3). On the basis of NMR spectroscopic and X-ray diffraction studies, the cation can be described as a combination of an amino-2-phosphaallylic cation and its methylated derivative.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 411-414 
    ISSN: 0009-2940
    Keywords: Phosphaalkyne, amino- ; [3 + 2] Cycloaddition ; 1,2,4-Diazaphospholes ; 1,2,3-Diazaphospholes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive E = C(p - p)π Systems, XXXII[1].  -  First Representatives of Amino-Substituted 1,2,4-Diazaphospholes(Diisopropylamino)phosphaethyne iPr2N - C≡P reacts at 20° C in a [3 + 2] cycloaddition with (trifluoromethyl)diazomethane (2a) or methyl diazoacetate (2b) to yield a mixture of the corresponding regioisomers 1H-1,2,4-diazaphospholes (5a or 5b) and 1H-1,2,3-diazaphospholes (6a or 6b) in quantitative yields (isomer ratio: 5a/6a = 2:1; 5b/6b = 4:1). X-ray diffraction studies on 5a and 5b indicate a delicate charge balance in the bonding system of 1H-1,2,4,σ2-diazaphospholes under the influence of the exocyclic push/pull substituents iPr2N and CF3 or CO2Me, respectively.
    Additional Material: 2 Ill.
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  • 7
    ISSN: 0009-2940
    Keywords: Phosphaalkyne, amino- ; Nickel carbonyl phosphane complex ; π Coordination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive E = C(p-p)π Systems, XXXIII.  -  Side-on Coordination of the Phosphaalkyne P ≡ C  -  N(iPr)2 in the 16e Nickel(0) Complex Ni(CO)PCy3[PCN(iPr)2]The reaction of (diisopropylamino)phosphaethyne P ≡ C  -  N(iPr)2 with the nickel complex [Ni(CO)3PCy3] - in contrast to the analogous reactions with Ni(CO)4 or Ni(CO)3PR3 (R = Me, Ph) - leads to the novel 16e nickel(0) system [Ni{η2-P ≡ C  -  N(iPr2)}(CO)PCy3] with a planar geometry of all skeleton atoms besides the methyl and cyclohexyl groups. Side-on coordination of the P ≡ C triple bond results in an increase of the PC distance to 1.665 Ȧ typical for phosphaalkenes.
    Additional Material: 1 Ill.
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  • 8
    ISSN: 0009-2940
    Keywords: Methylcarbene complexes of chromium and tungsten ; Cyclohexadienyl tricarbonyliron, carbene derivatives of ; Cycloheptadienyl tricarbonyliron, carbene derivatives of ; Cycloheptatrienyl, carbene derivatives of ; Enol ether, elimination from carbene complexes ; Spirocyclopropanes, elimination from carbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 71[1].  -  Methylcarbene Complexes of Chromium and Tungsten with Cycloheptatrienyl-, Cyclohexadienyl[Fe(CO)3]- and Cycloheptadienyl[Fe(CO)3] SubstituentsMethylcarbene complexes LnM=C(OEt)CH3 1 [LnM = (CO)5Cr, (CO)5W] react with tropylium tetrafluoroborate (2a) or coordinated olefins of [C6H7Fe(CO)3]BF4 (2c), [C7H9Fe-(CO)3]BF4 (2d), and [C7H7Fe2(CO)6]BF4 (2d) in the presence of Et3N to give complexes LnM=C(OEt)CH2R 3a-e and LnM=C(OEt)CHR2 7a-d by substitution of one or two α-hydrogen atoms. The trimetallic WFe2 carbene complexes 7c, d derived from 1b with 2c, d form three stereoisomers each, which are fully characterized spectroscopically, (R*,R*,S*)-7c additionally also by an X-ray structure analysis, Ligand elimination from 3 and 7 may involve a-and/or β-hydrogen transfer reactions: Thus enol ethers (Z/E)-6 are eliminated from α-monosubstituted methylcarbene complexes 3a, c, d in yields of 62-90% by a pyridine-induced transfer of an α-hydrogen to the carbene carbon atom; with increasing steric demand of R the elimination of the (Z) isomer (Z)-6 from 3 is favoured over the formation of the (E) isomer (E)-6. The enol ether 10 becomes a minor side product in the pyridine-induced ligand elimination from α-disubstituted complexes 7a, b. In these cases the spirocyclopropane 8 is formed as the main product (60-82%) besides the 4,5-homotropylidene 9 by a conformationally directed β-hydrogen transfer reaction.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0009-2940
    Keywords: 1,2-Dihydro-1,3,2λ5,4λ5-diazadiphosphete ; Isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Dihydro-1,3,2λ5,4λ5-diazadiphosphete - Synthesis, Structure and Isomerization to the „Inner Salt“ of 1,3,2,4λ5-Diazadiphosphetan-2-ium HydroxideThe photochemical reaction of the azidophosphane (iPr2N)2PN3 (1) with the tetraazaphospholene (3) and the bis(imino)phosphorane (Me3Si)2NP(=NSiMe3)2 (6) proceeds by elimination of N2 to yield (5) and by 1,3-silyl group shift to furnish (8) the structures of which were determined by means of NMR data and, in the case of 5, additionally by X-ray structure analysis.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2475-2482 
    ISSN: 0009-2940
    Keywords: Vinylcarbene complexes ; Chromium complexes ; Tungsten complexes ; Phosphorus ylide complexes ; Alkynylcarbene complexes ; Allene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkynylcarbene complexes (CO)5M≡C(OEt)-C≡C—R 1 (M = Cr, W; R = Ph, tBu, SiMe3) readily add tertiary phosphanes PPhR2′ 4 (R′ = Ph, Me) to form stable zwitterionic phosphonium allenide complexes (CO)5M--C(OEt) = C≡C(R)-P+PhR2′ 5. Complex 5a (M = Cr, R = R′ = Ph) was characterized by X-ray diffraction. The addition of secondary phosphanes PHR2 6 to 1 affords red (2-phosphanyl ethenyl)-carbene complexes (CO)5M≡C(OEt)-CH≡C(R)-PR2 (E)-8 (R = tBu, cC6H11, Ph) in 34-89% isolated yields. Dinuclear complexes (CO)5M≡C(OEt)-CH≡C(R)-P(R2)M(CO)5 (E)-9 are obtained as byproducts. Compounds (E)-8b (M = Cr, R = cC6H11) and (E)-9i (M = Cr, R = Ph) were characterized by X-ray analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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