- Candida Rugosa lipase-catalyzed kinetic resolution of β-hydroxy- β-arylpropionates and δ-hydroxy-δ-aryl-β-oxo-pentanoates
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A simple and convenient method was reported for the preparation of optically active β-hydroxy-β-arylpropionates, δ-hydroxy-δ- aryl-β-oxo-pentanoates and their butyryl derivatives via CRL-catalyzed hydrolysis. The optically active products are potential precursors of some chiral pharmaceuticals and natural products.
- Xu, Chengfu,Yuan, Chengye
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p. 2169 - 2186
(2007/10/03)
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- Inversion of enantioselectivity during the platinum-catalyzed hydrogenation of an activated ketone
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Two competing reaction pathways, which lead to opposite enantiomers (see scheme), occur in the hydrogenation of 1 over chirally modified platinum, as revealed by catalytic and NMR spectroscopic experiments: the fast reduction of the ketoform 1a (minor species) and the slow hydrogenolysis of the hydrate 3 (major species).
- Von Arx, Matthias,Mallat, Tamas,Baiker, Alfons
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p. 2302 - 2305
(2007/10/03)
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- Regioselectivity in the Ring Opening of 2-Alkylcyclopropylmethyl Radicals: the Effect of Electronegative Substituents
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The regioselectivity of the ring-opening of the trans-2-alkylcyclopropylmethyl radical A to give the primary alkyl radicals B, or the secondary alkyl radicals C, has been investigated, where the groups R and/or CXY carry electronegative substituents.All these reactions gave principally the secondary alkyl radicals C, whereas, in the absence of electronegative substituents, ring-opening occurs in favour of the primary alkyl radicals B.This regioselectivity is interpreted in terms of the frontier orbital interactions which are involved.
- Ratier, Max,Pereyre, Michel,Davies, Alwyn G.,Sutcliffe, Roger
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p. 1907 - 1916
(2007/10/02)
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