- On the role of PIII ligands in the conjugate addition of diorganozinc derivatives to enones
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A mechanistic study on the conjugate addition of diethylzinc to cyclohexenone catalyzed by various chiral PIII ligands, provides new insights into its mechanism. Complete in situ conversion of the catalytic amount of Cu(OTf)2 into Cu
- Pfretzschner, Tatjana,Kleemann, Lutz,Janza, Birgit,Harms, Klaus,Schrader, Thomas
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- Development, mechanism, and scope of the palladium-catalyzed enantioselective allene diboration
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In the presence of a chiral phosphoramidite ligand, the palladium-catalyzed diboration of allenes can be executed with high enantioselectivity. This reaction provides high levels of selectivity with a range of aromatic and aliphatic allene substrates. Iso
- Burks, Heather E.,Liu, Shubin,Morken, James P.
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Read Online
- Preparation and characterization of new C2- and C 1-symmetric nitrogen, oxygen, phosphorous, and sulfur derivatives and analogs of TADDOL. part II
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TADDOL (=α,α,α′,α′-Tetraaryl-1,3- dioxolane-4,5-dimethanol) and the corresponding dichloride are converted to TADDAMINs (=(4S,5S)-2,2,N,N′-tetramethyl-α,α,α′, α′-tetraphenyl-1,3-dioxolan-4,5-dimethanamines) (Scheme 2) and ureas, 12-15, and to TADDOP derivatives with seven-membered O-P-O ester rings (Schemes 3 and 4). Cl/P-Replacement via the Michaelis-Arbuzov reaction (Scheme 7) on mono- and dichlorides, derived from TADDOL, are described. It was not possible to obtain phosphines with the P-atom attached to the benzhydrylic C-atom of the TADDOL skeleton (Schemes 6 and 7). The X-ray crystal structures (Figs. 1 and 2) of ten of the more than 30 new TADDOL derivatives are discussed. Full experimental details are presented. Copyright
- Pichota, Arkadius,Gramlich, Volker,Bichsel, Hans-Ulrich,Styner, Thomas,Knoepfel, Thomas,Wuensch, Ralf,Hintermann, Tobias,Schweizer, W. Bernd,Beck, Albert K.,Seebach, Dieter
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experimental part
p. 1273 - 1302
(2012/10/07)
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- Enantioselective synthesis of Indolizidines bearing quaternary substituted stereocenters via rhodium-catalyzed [2 + 2 + 2] cycloaddition of alkenyl Isocyanates and terminal alkynes
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An enantioselective synthesis of Indolizidines bearing quaternary substituted stereocenters by way of a rhodium-catalyzed [2 + 2 + 2] cycloaddition of substituted alkenyl Isocyanates and terminal alkynes Is described. The reaction provides lactam products using aliphatic alkynes, whereas aryl alkynes give rise to vlnylogous amide products. Through modification of the phosphoramldlte llgand, high levels of enantloselectlvlty, regloselectlvlty, and product selectivity are obtained for both products.
- Lee, Ernest E.,Rovis, Tomislav
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supporting information; body text
p. 1231 - 1234
(2009/04/07)
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- Synthesis and application of chiral phosphorus ligands derived from TADDOL for the asymmetric conjugate addition of diethyl zinc to enones
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Asymmetric conjugate addition of diethylzinc to cyclohexen-2-one, chalcone, and benzalacetone has been found to occur with 0.5% copper(II) triflate and 1% chiral phosphite. Cyclic phosphites derived from TADDOL gave excellent to moderate enantiomeric exce
- Alexakis, Alexandre,Burton, Jonathan,Vastra, Johann,Benhaim, Cyril,Fournioux, Xavier,Van Den Heuvel, Alexandra,Leveque, Jean-Marc,Maze, Frederique,Rosset, Stephane
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p. 4011 - 4027
(2007/10/03)
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