- One-Pot Absolute Stereochemical Identification of Alcohols via Guanidinium Sulfate Crystallization
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A novel technique for the absolute stereochemical determination of alcohols has been developed that uses crystallization of guanidinium salts of organosulfates. The simple one-pot, two-step process leverages facile formation of guandinium organosulfate single crystals for the straightforward determination of the absolute stereochemistry of enantiopure alcohols by means of X-ray crystallography. The strong hydrogen bonding network drives the stability of the crystal lattice and allows for a diverse range of organic alcohol substrates to be analyzed.
- Brummel, Beau R.,Lee, Kinsey G.,McMillen, Colin D.,Kolis, Joseph W.,Whitehead, Daniel C.
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p. 9622 - 9627
(2019/12/02)
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- Dynamic kinetic asymmetric transformation of 1,4-diols and the preparation of trans-2,5-disubstituted pyrrolidines
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Dynamic kinetic asymmetric transformation (DYKAT) of a series of 1,4-diols is carried out with Candida antarctica lipase B (CALB), Pseudomonas cepacia lipase II (PS-C II), and a ruthenium catalyst. A β-chloro-substituted 1,4-diol is successfully transformed into an optically pure 1,4-diacetate, which is a highly useful synthetic intermediate. The usefulness of the optically pure 1,4-diacetates is demonstrated by the synthesis of enantiopure 2,5-disubstituted pyrrolidines.
- Borén, Linnéa,Leijondahl, Karin,B?ckvall, Jan-E.
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supporting information; experimental part
p. 3237 - 3240
(2009/08/17)
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- Stereoselective reduction of unsaturated 1,4-diketones. A practical route to chiral 1,4-diols
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A new synthetic route to C2-symmetric chiral 1,4-diols based on the borane-mediated oxazaborolidine-catalysed reduction of 2-ene-1,4-diones (2), of 2-yne-1,4-diones (3), and/or of Co-complexed diketones 4 is described. Good to excellent enantio- and diastereoselectivities have been obtained in the reduction of diketones 3 and 4, catalysed by oxazaborolidines 6 and 5, respectively.
- Bach, Jordi,Berenguer, Ramon,Garcia, Jordi,Loscertales, Teresa,Manzanal, Judith,Vilarrasa, Jaume
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p. 1091 - 1094
(2007/10/03)
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- New chiral phospholanes; synthesis, characterization, and use in asymmetric hydrogenation reactions
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We describe the practical synthesis of enantiomerically pure trans-2,5-disubstituted-1-phenylphospholanes which are then employed in the preparation of a new series of C2-symmetric bis- and C3-symmetric tris(phospholane) ligands. A versatile three-step route to the important chiral 1,4-diol intermediates, used in the phosphine syntheses, is outlined. Rhodium complexes bearing the new phosphine ligands were prepared and shown to act as efficient catalyst precursors for the enantioselective hydrogenation of various unsaturated substrates.
- Burk,Feaster,Harlow
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p. 569 - 592
(2007/12/18)
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