499783-11-8Relevant articles and documents
Enantioselective alkylation of aldehydes promoted by (S)-tyrosine-derived β-amino alcohols
Wolf, Christian,Francis, Christopher J.,Hawes, Pili A.,Shah, Mirage
, p. 1733 - 1741 (2002)
Two (S)-tyrosine-derived β-amino alcohols exhibiting a secondary and tertiary amino moiety, respectively, were employed in the enantioselective alkylation of aldehydes using diethylzinc. The enantioselectivity, catalytic activity and substrate specificity of these precatalysts were compared by high-throughput screening of benzaldehyde, cyclohexanecarboxaldehyde and hexanal. The homochiral catalysts were found to exhibit opposite chiral induction. The secondary amino alcohol favors the formation of (S)-alcohols, whereas the tertiary amino alcohol provides (R)-alcohols. Enantioselectivity and sense of chiral induction obtained with the secondary amino alcohol was proven to depend on the choice of solvent and experimental procedure. The mechanism of the enantioselective ethylation of benzaldehyde promoted by (S)-tyrosine-derived β-amino alcohols was studied by stoichiometric experiments and MM2 computations.
