- New Access Routes to Privileged and Chiral Ligands for Transition-Metal Catalyzed Hydrogen Autotransfer (Borrowing Hydrogen), Dehydrogenative Condensation, and Alkene Isomerization Reactions
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A group of transition-metal catalyzed hydrogen moving reactions, encompassing hydrogen autotransfer (HAT; also called borrowing hydrogen, BH), dehydrogenative condensation (DHC) and alkene isomerization, displays high atom economy and relies on widely ava
- Hintermann, Lukas,Jandl, Christian,Klein, Philippe,Koller, Sebastian,Ochmann, Lukas,P?thig, Alexander,Reinhardt, Katja,Seitz, Antonia
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- Nucleophilic substitution of p-stereogenic chlorophosphines: Mechanism, stereochemistry, and stereoselective conversions of diastereomeric secondary phosphine oxides to tertiary phosphines
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A diastereomeric mixture of secondary phosphine oxide is stereospecifically converted to chlorophosphine salt by treatment with oxalyl chloride, which stereoselectively affords P-inverted or retained tertiary phosphines, depending on the substitution with aliphatic or aromatic Grignard reagents, respectively, in high to 99% yield and 99:1 dr. The repulsion of π- electron on aryl to lone electron pair on phosphorus is proposed for the P-retained substitution.
- Ye, Jing-Jing,Nie, Shao-Zhen,Wang, Ji-Ping,Wen, Jing-Hong,Zhang, Yu,Qiu, Mao-Ran,Zhao, Chang-Qiu
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p. 5384 - 5387
(2017/11/07)
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- Crystallization-Induced Asymmetric Transformation of a Tertiary Phosphine
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An equilibrating diastereomer mixture of the tertiary phosphines 5 and 6 (2.5:1 equilibrium ratio) undergoes crystallization-induced asymmetric transformation upon slow evaporation of solvent from refluxing heptane to give a 20:1 ratio in favor of the more stable crystalline isomer 5. The process can also be carried out at room temperature by using iodine to catalyze the interconversion of 5 and 6 via a pentavalent intermediate 8. However, this variation is more sensitive to the purity of the starting phosphine. Crystalline 5 can be converted to the stable borane complex 3, and reductive cleavage of the fluorenyl group using lithium naphthalenide affords the corresponding lithio derivative 10. Alkylation with iodomethane or benzyl bromide affords 13 or 17, respectively, with retention of phosphorus configuration.
- Vedejs, Edwin,Donde, Yariv
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p. 2337 - 2343
(2007/10/03)
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- Determination of the absolute configurations of the epimers of the P-chiral phosphine Ph2PCH2CH2P*Ph(L-(-)-menthyl) by use of two-dimensional NMR spectroscopy in combination with a palladium(II) "reporter complex"
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The two epimers of the new P-chiral phosphine Ph2PCH2CH2P*Ph(L-(-)-menthyl) (1-Rp and 1-Sp) were synthesized by treating Ph2PH with the diastereometrically pure forms of Ph(L-(-)-menthyl)CH=CH2)P.The palladium(II) complexes , 2-Rp, and , 2-Sp, were obtained by treating the corresponding bisphosphines with .Each of these complexes exists in the form of two regioisomers differing in the orientation of the chiral phosphine relative to the C-donor.Constraints from close interligand, intramolecular hydrogen-hydrogen contacts within three of these palladium complexes were detected by two-dimensional NOE spectroscopy, and were used to determine the absolute configurations at the chiral phosphorus centers in the Ph2PCH2CH2PPh(L-(-)-menthyl)isomers.The conformations of the two chelate rings in the more abundant of these isomers were also determined. Keywords: Chiral phosphine; Absolute configuration; Two-dimensional NMR; Palladium; Solution structure
- Jiang, Qiongzhong,Rueegger, Heinz,Venanzi, Luigi M.
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p. 233 - 240
(2007/10/03)
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- Menthyl-substituted Organophosphorus Compounds. Part 6. Preparation of P(L-men)RCl and P(L-men)R(S)Cl (R = Me, Et, iPr, tBu, OR Ph; men = cyclo-C6H9-2-iPr-5-Me) and Nuclear Magnetic Resonance Studies of Configuration and Halogen Exchange
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Menthyl-substituted chlorophosphines P(L-men)RCl and thiophosphoryl chlorides P(L-men)R(S)Cl (R = Me, Et, or iPr; men = menthyl, i.e. 2-isopropyl-5-methylcyclohexyl) have been prepared.These series (including compounds with R = Ph and tBu) were subjected
- Haegele, Gerhard,Kueckelhaus, Wolfgang,Tossing, Gudrun,Seega, Juergen,Harris, Robin K.,et al.
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p. 795 - 806
(2007/10/02)
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