✦ LIBER ✦

Asymmetric aldol addition of aldehydes to a difluoroketene silyl acetal catalyzed by chiral Lewis acids

✍ Scribed by Katsuhiko Iseki; Yoshichika Kuroki; Daisuke Asada; Mie Takahashi; Satoshi Kishimoto; Yoshiro Kobayashi

Book ID: 104207956
Publisher: Elsevier Science
Year: 1997
Tongue: French
Weight: 667 KB
Volume: 53
Category: Article
ISSN: 0040-4020
DOI: 10.1016/s0040-4020(97)00683-2

No coin nor oath required. For personal study only.

✦ Synopsis

Aldol reaction of aldehydes with difluomketene ethyl trimethylsilyl acetal (1) in the presence of a substoichiometric amount of chiral Lewis acid 2 or 3 provides the corresponding ~,a-difluom hydroxy esters 4-12 with high enantioselectivitles (up to 98% ee). Reaction temperature has a great influence on the enantiofacial selection of aldehydes; the reactions of benzyloxyacetaldehyde catalyzed by Lewis acid 2 at -78 and -30"C gave the (+)-and (-)-¢x,~-difluom ~hydroxy esters 7 in optical yields of 98% and 85%, respectively.

📜 SIMILAR VOLUMES

ChemInform Abstract: Asymmetric Aldol Ad

ChemInform Abstract: Asymmetric Aldol Addition of Aldehydes to a Difluoroketene Silyl Acetal Catalyzed by Chiral Lewis Acids.

✍ K. ISEKI; Y. KUROKI; D. ASADA; M. TAKAHASHI; S. KISHIMOTO; Y. KOBAYASHI 📂 Article 📅 2010 🏛 John Wiley and Sons ⚖ 38 KB 👁 2 views

Enantioselective aldol reaction with a b

Enantioselective aldol reaction with a bromofluoroketene silyl acetal catalyzed by a chiral Lewis acid

✍ Katsuhiko Iseki; Yoshichika Kuroki; Yoshiro Kobayashi 📂 Article 📅 1997 🏛 Elsevier Science 🌐 French ⚖ 138 KB

Lewis Base Activation of Lewis Acids. Vi

Lewis Base Activation of Lewis Acids. Vinylogous Aldol Addition Reactions of Conjugated N,O-Silyl Ketene Acetals to Aldehydes.

✍ Scott E. Denmark; John R. Jr. Heemstra 📂 Article 📅 2006 🏛 John Wiley and Sons ⚖ 30 KB 👁 2 views

Lewis Base Activation of Lewis Acids. Vi

Lewis Base Activation of Lewis Acids. Vinylogous Aldol Addition Reactions of Conjugated N , O -Silyl Ketene Acetals to Aldehydes

✍ Denmark, Scott E.; Heemstra, John R. 📂 Article 📅 2006 🏛 American Chemical Society 🌐 English ⚖ 100 KB

Asymmetric cyclization of unsaturated al

Asymmetric cyclization of unsaturated aldehydes catalyzed by a chiral lewis acid

✍ Soichi Sakane; Keiji Maruoka; Hisashi Yamamoto 📂 Article 📅 1985 🏛 Elsevier Science 🌐 French ⚖ 254 KB

A highly enantioselective cyclization of prochiral unsaturated aldehydes has been accomplished with a chiral zinc reagent derived from dimethylzinc and (R)-(+)-l,l'-bi-2-naphthol. Of the available methods for constructing multicarbocyclic structures, cationic polyolefin cyclization, a synthetic str

Asymmetric cyclization of unsaturated al

Asymmetric cyclization of unsaturated aldehydes catalyzed by a chiral lewis acid

✍ Soichi Sakane; Keiji Maruoka; Hisashi Yamamoto 📂 Article 📅 1986 🏛 Elsevier Science 🌐 French ⚖ 675 KB