Asymmetric induction in the zirconium catalyzed ethylmagnesiation reaction
- Univ. of Southampton, Hants (United Kingdom)
In 1985 Dzhemilev reported the zirconium catalysed ethylmagnesiation of terminal alkenes. A chiral centre is formed during the reaction which occurs under mild conditions. The authors have applied this reaction to a number of substrates and a mechanism has been elucidated. In order to induce asymmetry into the reaction, several chiral literature catalysts were synthesised including Ethylenebis(tetrahydroindenyl)zirconium dichloride and two more hindered complexes reported by Erker. All of these catalysts displayed low activity and poor asymmetric induction with terminal alkenes. The synthesis and properties of two novel catalysts will be described. Results show high activity furnishing carbomagnesiated products in excellent yields with as little as 2 mol% catalyst. The enantiomeric excesses induced by the complexes are as high as 79% with terminal alkenes but are >95% with cyclic ethers. The catalyst has proved recoverable. Ethylmagnesiation of an amine followed by an acidic workup furnishes the chiral complex in a quantitative return.
- OSTI ID:
- 250103
- Report Number(s):
- CONF-9508100-; TRN: 96:002623-0041
- Resource Relation:
- Conference: 8. IUPAC symposium on organometallic chemistry directed towards organic synthesis, Santa Barbara, CA (United States), 6-10 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of Eight IUPAC symposium on organometallic chemistry directed towards organic synthesis (OMCOS 8); PB: 375 p.
- Country of Publication:
- United States
- Language:
- English
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