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Configurational Stability of Oxymethyllithiums as Intermediates in Intramolecular Rearrangements

✍ Scribed by Dagmar C. Kapeller; Lothar Brecker; Friedrich Hammerschmidt

Book ID
101834561
Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
294 KB
Volume
13
Category
Article
ISSN
0947-6539

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✦ Synopsis

Abstract

Several homochiral oxymethyllithiums, chiral by virtue of the hydrogen isotopes protium and deuterium, were prepared. They were tested for their microscopic configurational stability in intramolecular isomerizations, such as the silyl‐ and germyl‐[1,2]‐retro‐Brook and the sigmatropic[2,3]‐Wittig rearrangement. The influence of temperature, solvent, and migrating group on the stability of the intermediate carbanions was studied. Furthermore, the stereochemical course of these rearrangements was elucidated, resulting in highly enantioenriched alcohols (90–97 % ee; ee=enantiomeric excess) up to temperatures of 0 °C.

📜 SIMILAR VOLUMES

Ion pairs as intermediates in the rearra
Ion pairs as intermediates in the rearrangements of the dibenzocycloheptatrienyl-methyl and dibenzocyclooctatrienyl systems
✍ Ecaterina Cioränescu; Aurora Bucur; M. Elian; M. Banciu; M. Voicu; C.D. Nenitzes 📂 Article 📅 1964 🏛 Elsevier Science 🌐 French ⚖ 218 KB

By acetolysis of the 1:2.5:6-dibensocyclohepta-1.3.5trienyl-T-methyl tosylate (Ib) in glacial acetic acid the unrearranged acetate Ic was obtained together with a small amount of dibenzocyclooctatetraene (III). On the other hand 1:2.5:6-dibenzocycloocta-1.5.5-triene-T-01 acetate (IIb) was t'ne only