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Synfacts 2006(4): 0346-0346  
DOI: 10.1055/s-2006-932049
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Carbohydrate-Derived Ligands for Asymmetric Alkynylation

Contributor(s): Mark Lautens, Josephine Yuen
D. P. G. Emmerson, W. P. Hems, B. G. Davis*
University of Oxford, UK
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Publication History

Publication Date:
24 March 2006 (online)

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Significance

A range of carbohydrate-derived amino alcohol ligands were investigated in the Zn(OTf)2-mediated addition of alkynes to aldehydes and in some cases excellent enantioselectivities were observed. Cyclic amine substituents at the C2 position of the gluco ligands gave higher enantioselectivities and yields than acyclic ones. β-Gluco ligands gave higher selectivity than the α-anomers. It is likely that the morpholinyl oxygen coordinates to zinc in the transition state. This oxygen might also act as a Lewis base activating the zinc acetylide.