Synthesis 2006(18): 3099-3105  
DOI: 10.1055/s-2006-950205
PAPER
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Alkynylation Reactions to Aldehydes: The Effects of Aromatic Substituents upon the Enantioselectivity

Elizabeth Tyrrell*, Kibur Hunie Tesfa, Julien Millet, Christophe Muller
School of Pharmacy and Chemistry, Kingston University, Penrhyn Road, Kingston, Surrey, KT1 2EE, UK
Fax: +44(20)85477562; e-Mail: e.tyrrell@kingston.ac.uk;
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Publikationsverlauf

Received 19 April 2006
Publikationsdatum:
21. August 2006 (online)

Abstract

Asymmetric alkynylation reactions to linear alkyl and substituted aromatic aldehydes have been accomplished in good yields and with a range of selectivities. For aromatic aldehydes we observed that the selectivity of the alkynylation reaction appears to depend upon the substituents on the aromatic ring. Thus with electron-withdrawing substituents both the yield and enantioselectivities were good to excellent. In contrast to this, the presence of electron-donating groups provided excellent conversions; however, these were coupled with poor enantioselectivities.

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The results from these studies will be disseminated at a later date (although see ref. 4).

19

All compounds provided satisfactory spectral data that were consistent with the assigned structures. For succinctness we have limited the experimental section to a representative example of salicylaldehyde derivatives, e.g. non-substituted, mono- and di-substituted and naphthyl derivatives. Optical rotation data and HPLC retention times are included for all relevant examples.