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ABSTRACT: Persistent chlorine: Hydrogenation of borolane-substituted vinylic chlorides catalyzed by IrP^N complexes greatly preserved the chlorine substituent on the hydrogenated product, with only 3-19 % of dechlorinated byproducts present after hydrogenation. The α-chloro boronic ester products are ideal precursors for proteasome-inhibitor-type anti-cancer drugs, a fact which demonstrates the utility of this hydrogenation protocol.
Angewandte Chemie International Edition 12/2011; 51(4):1014-8. · 13.45 Impact Factor
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ABSTRACT: Asymmetric hydrogenation is one of the most important catalytic methods for the preparation of optically active compounds. For a long time the range of olefins that could be hydrogenated with high enantiomeric excess was limited to substrates bearing a coordinating group next to the C+C bond. We have found a new class of catalysts, iridium complexes with chiral P, N ligands, that overcome these limitations. For a wide range of unfunctionalized olefins, excellent enantioselectivities could be achieved. Because these catalysts do not require the presence of any particular functional group in the substrate, they considerably broaden the scope of asymmetric hydrogenation. In addition, promising results were also obtained with certain functionalized alkenes, furans, and benzofurans.
Accounts of Chemical Research 01/2008; 40(12):1402-11. · 21.64 Impact Factor
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ABSTRACT: [reaction: see text] A highly diastereoselective intramolecular nitrone cycloaddition onto a chiral ketene equivalent, obtained by Horner-Wadsworth-Emmons olefination of either enantiomer of bis-sulfinyl phosphonate 6, is described. Cycloaddition gave 5,5-disubstituted isoxazolidine 10 in good yield as a single diastereomer. Catalytic hydrogenolysis of 10 furnished either enantiomer of optically pure cis-2-aminocyclopentane-1-carboxylic acid.
Organic Letters 05/2002; 4(7):1227-9. · 5.86 Impact Factor
