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Asymmetric cyclization of unsaturated aldehydes catalyzed by a chiral lewis acid

✍ Scribed by Soichi Sakane; Keiji Maruoka; Hisashi Yamamoto

Book ID
104233323
Publisher
Elsevier Science
Year
1985
Tongue
French
Weight
254 KB
Volume
26
Category
Article
ISSN
0040-4039

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✦ Synopsis

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 strategy that mimics the key biosynthetic transformation leading to polycyclic .

triterpenes, seems to have the highest potential.' Although these cyclizations proceed stereospecific with respect to the relative configurations of the chiral centers, the products were always racemic .

Consequently, the only remaining, formidable problem is to explore an effective method for asymmetric

πŸ“œ SIMILAR VOLUMES

Asymmetric aldol addition of aldehydes t
Asymmetric aldol addition of aldehydes to a difluoroketene silyl acetal catalyzed by chiral Lewis acids
✍ Katsuhiko Iseki; Yoshichika Kuroki; Daisuke Asada; Mie Takahashi; Satoshi Kishim πŸ“‚ Article πŸ“… 1997 πŸ› Elsevier Science 🌐 French βš– 667 KB

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 influenc