- Chiral ytterbium complex-catalyzed direct asymmetric aldol-tishchenko reaction: Synthesis of anti-1,3-diols
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The asymmetric aldol-Tishchenko reaction of aromatic aldehydes with aliphatic and aromatic ketones has been developed as an efficient strategy for the synthesis of anti-1,3-diols in good yield with high diastereo-control and good levels of enantiose-lectivity. This domino-type reaction is catalyzed by a chiral ytterbium complex that promotes both the aldol reaction through enolization of the carbon yl compound and the Evans-Tishchenko reduction of the aldol intermediate. The stereochemistry of the resulting diols is also investigated and finally proved by using CD techniques.
- Mlynarski, Jacek,Rakiel, Bartosz,Stodulski, Maciej,Suszczynska, Agata,Frelek, Jadwiga
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- New chiral catalysts for the highly enantioselective addition of diethylzinc to aldehydes
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Optically active amino thioacetate derivatives of (+)-norephedrine were found to act as effective catalysts for enantioselective addition of diethylzinc to aldehydes. This reaction provided optically active secondary alcohols with e.e. of up to >99%.
- Jin, Myung-Jong,Ahn, Sum-Jin,Lee, Kyoung-Soo
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p. 8767 - 8770
(2007/10/03)
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- Chiral N,N-Dialkylnorephedrines as Catalysts of the Highly Enantioselective Addition of Dialkylzincs to Aliphatic and Aromatic Aldehydes. The Asymmetric Synthesis of Secondary Aliphatic and Aromatic Alcohols of High Optical Purity
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The chiral N,N-dialkylnorephedrine-catalyzed addition of dialkylzincs to aliphatic and aromatic aldehydes afforded secondary alcohols of high optical purity (to > 95percent ee).Among the N,N-di(primary alkyl)norephedrines, N,N-di-n-butylnorephedrine (DBNE, 3d) was found to be the most effective catalyst. 1-Phenyl-2-(1-pyrrolidinyl)propan-1-ol (3i) and N,N-diallylnorephedrine (3j) were also highly effective catalysts.The method described provides optically active secondary aliphatic alcohols of high optical purity which cannot be prepared by conventional methods.
- Soai, Kenso,Yokoyama, Shuji,Hayasaka, Tomoiki
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p. 4264 - 4268
(2007/10/02)
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- A New Chiral Catalyst for the Highly Enantioselective Addition of Dialkylzinc Reagents
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Even purely aliphatic aldehydes, as well as aromatic aldehydes, were alkylated enantioselectively with dialkylzinc reagents in high enantiomeric excess using (1) as a chiral catalyst.
- Soai, Kenso,Yokoyama, Shuji,Ebihara, Katsumi,Hayasaka, Tomoiki
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p. 1690 - 1691
(2007/10/02)
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