331993-83-0Relevant articles and documents
Enantioselective synthesis of cyclic enol ethers and all-carbon quaternary stereogenic centers through catalytic asymmetric ring-closing metathesis
Lee, Ai-Lan,Malcolmson, Steven J.,Puglisi, Alessandra,Schrock, Richard R.,Hoveyda, Amir H.
, p. 5153 - 5157 (2006)
The first examples of catalytic asymmetric ring-closing metathesis (ARCM) reactions of enol ethers are reported. To identify the most effective catalysts, various chiral Mo- and Ru-based catalysts were screened. Although chiral Ru catalysts (those that do
Direct asymmetric aldol reactions in aqueous media catalyzed by a β-cyclodextrin-proline conjugate with a urea linker
Liu, Kegang,Zhang, Guoqi
, p. 243 - 246 (2014)
Covalently attaching proline to β-CD through a urea linkage resulted in the synthesis of a water-soluble chiral organocatalyst 1 in high yield. Catalytic asymmetric aldol condensations between aldehydes and acetone were carried out under water-containing
Enantioselective synthesis of cyclic allylboronates by Mo-catalyzed asymmetric ring-closing metathesis (ARCM). A one-pot protocol for net catalytic enantioselective cross metathesis
Jernelius, Jesper A.,Schrock, Richard R.,Hoveyda, Amir H.
, p. 7345 - 7351 (2004)
Mo-catalyzed asymmetric ring-closing metathesis (ARCM) reactions are used to synthesize cyclic allylboronates of high optical purity (89% ee to >98% ee). A one-pot procedure involving formation of allylboronates, Mo-catalyzed ARCM and functionalization of
Synthesis of Enantiomerically Pure β-Hydroxy Ketones via β-Keto Weinreb Amides by a Condensation/Asymmetric-Hydrogenation/Acylation Sequence
Diehl, Julian,Brückner, Reinhard
, p. 278 - 286 (2017/01/24)
An established route to enantiomerically pure β-hydroxy ketones proceeds through the asymmetric hydrogenation of β-keto esters, an ester/amide exchange, and the use of the resulting β-hydroxy amide for the acylation of an organometallic compound. We shortened this route by showing that β-keto Weinreb amides are hydrogenated with up to 99 % ee in the presence of [Me2NH2]+{[RuCl(S)-BINAP]2(μ-Cl)3}–(0.5 mol-%) at room temp./5 bar. These Weinreb amides were prepared by seemingly obvious yet unprecedented condensations of lithiated N-methoxy-N-methylacetamide with carboxylic chlorides (51–87 % yield). The resulting β-hydroxy Weinreb amides were used for the acylation of organolithium and Grignard reagents. They thus gave enantiomerically pure β-hydroxy ketones (28 examples). A selection of these compounds gave anti-1,3-diols after another C=O bond hydrogenation, or syn-1,3-diols by a Narasaka–Prasad reduction.
Improved conditions for the proline-catalyzed aldol reaction of acetone with aliphatic aldehydes
Martínez, Alberto,Zumbansen, Kristina,D?hring, Arno,Van Gemmeren, Manuel,List, Benjamin
supporting information, p. 932 - 934 (2014/05/06)
The proline-catalyzed asymmetric aldol reaction between aliphatic aldehydes and acetone has, to date, remained underdeveloped. Challenges in controlling this reaction include avoiding undesired side reactions such as aldol condensation and self-aldolization. In recent years we have developed optimized conditions, which enable high yields and good to excellent enantioselectivities, and which are presented in this communication. Georg Thieme Verlag Stuttgart New York.
Preparation of the Enantiomerically Enriched Isomers of the Odorous Cyclic Ethers Clarycet, Florol, and Rhubafuran by Enzymatic Catalysis
Abate, Agnese,Brenna, Elisabetta,Fronza, Giovanni,Fuganti, Claudio,Gatti, Francesco G.,Serra, Stefano,Zardoni, Enrica
, p. 765 - 780 (2007/10/03)
All the enantiomerically enriched stereoisomers of Clarycet (1), Florol (2), and Rhubafuran (3) were prepared by biocatalysis routes. Their absolute configurations were established, and their olfactory properties were fully evaluated.
High-pressure-promoted asymmetric aldol reactions of ketones with aldehydes catalyzed by L-proline
Sekiguchi, Yusuke,Sasaoka, Aika,Shimomoto, Ai,Fujioka, Shingo,Kotsuki, Hiyoshizo
, p. 1655 - 1658 (2007/10/03)
High-pressure conditions were applied to direct asymmetric aldol reactions between ketones and aldehydes with L-proline as a commercially available chiral amino acid catalyst.
Enantioselective synthesis of medium-ring heterocycles, tertiary ethers, and tertiary alcohols by Mo-catalyzed ring-closing metathesis
Kiely, Andrew F.,Jernelius, Jesper A.,Schrock, Richard R.,Hoveyda, Amir H.
, p. 2868 - 2869 (2007/10/03)
The Mo-catalyzed asymmetric ring-closing metathesis (ARCM) of various achiral trienes leads to the formation of medium-ring unsaturated heterocycles in high yield and with excellent enantioselectivity. Reactions may be carried out on gram scale and in the
Direct asymmetric aldol reactions of acetone using bimetallic zinc catalysts
Trost, Barry M.,Silcoff, Elliad R.,Ito, Hisanaka
, p. 2497 - 2500 (2007/10/03)
(Equation presented) The enantioselective aldol reaction using a novel binuclear zinc catalyst of acetone with several aldehydes gave products in good yields (62-89%) with a high level of enantioselectivity (ee = 76-92%).
Proline-catalyzed asymmetric aldol reactions between ketones and alpha-unsubstituted aldehydes.
List,Pojarliev,Castello
, p. 573 - 575 (2007/10/03)
[reaction: see text] With this communication we extend the methodology of proline-catalyzed direct asymmetric aldol reactions to include alpha-unsubstituted aldehydes as acceptors. This important aldehyde class gives the corresponding aldols in 22-77% yield and up to 95% ee when the reactions are performed in pure acetone or in ketone/chloroform mixtures. On the basis of these results we have developed a concise new synthesis of (S)-ipsenol.
