- Highly diastereoselective conjugate additions of monoorganocopper reagents to chiral imides
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Stereoselective conjugate additions to chiral N-enoyl amides employing various monoorganocuprate reagents, Li[RCuI], are described. The presence of TMSI in the addition of Li[RCuI] in THF provided the highest stereoselectivities. Reversed major diastereom
- Dambacher, Jesse,Anness, Robert,Pollock, Patrick,Bergdahl, Mikael
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p. 2097 - 2110
(2007/10/03)
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- High ?-Facial Selectivity Through Chelation of Magnesium Ions in the DMD Epoxidation of α,β-Unsaturated Imides with Chiral Pyrrolidinone Auxiliaries
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High diastereoselectivity, nut of the opposite sense, is observed in the epoxidation (DMD or mCPBA) of α,β-unsaturated imides equipped with pyrrolidinone-type chiral auxiliaries that bear either a hydroxymethyl or trityloxymethyl side chain. This unprecedented reversed ?-facial differentiation is promoted by chelation of a magnesium ion, which results in conformational control over the essential steric interactions.
- Adam, Waldemar,Zhang, Aimin
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p. 147 - 152
(2007/10/03)
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- Diastereoselectivity in the Preparation of β-Silyl Esters from αβ-Unsaturated Esters and Amides Attachhed to Chiral Auxiliaries
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The conjugate addition of the phenyldimethylsilyl-cuprate reagent to cinnamate and crotonate esters and amides 1 of various known chiral auxiliaries, a-e, is diastereoselective.The sense of diastereoselectivity of silyl-cuprate addition to the esters 1b-d, 8 and 9 is different from established precedent based on carbon-cuprates, but is normal for silyl-cuprate addition to the amide 1a, the imines 1e and 21, and the oxazolidine 6.The chiral auxiliary e gives the best results of those tested, and the silicon-containing group can be removed from the chiral auxiliary using alkoxide ion in aprotic media, making available β-silyl esters 27-29 of high enantiomeric excess, with recovery of the chiral auxiliary 30.
- Fleming, Ian,Kindon, Nicolas D.
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p. 303 - 316
(2007/10/02)
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