Direct organocatalytic asymmetric aldol reactions of alpha-amino aldehydes: expedient syntheses of highly enantiomerically enriched anti-beta-hydroxy-alpha-amino acids.

[reaction: see text] A simple and efficient method for the synthesis of highly enantiomerically enriched beta-hydroxy-alpha-amino acid derivatives has been developed. Direct asymmetric aldol reactions of a glycine aldehyde (aminoacetaldehyde) derivative have been performed under organocatalysis using l-proline or (S)-5-pyrrolidine-2-yl-1H-tetrazole. The reactions afforded anti-beta-hydroxy-alpha-amino aldehydes in good yield with high diastereoselectivity (dr up to >100:1) and high enantioselectivity (up to >99.

Expanding the Potential of DNA for Binding and Catalysis: Highly Functionalized dUTP Derivatives That Are Substrates for Thermostable DNA Polymerases.

The discovery of a simple structural motif allows for the enzymatic synthesis by polymerase chain reactions (PCR) of modified DNA (see reaction scheme) bearing side chains similar or even identical to those of several amino acids. Libraries of DNA functionalized with both cationic and anionic groups may now be readily prepared. R=I, HgCl; X=functional group.

Catalytic Enantioselective Retro-Aldol Reactions: Kinetic Resolution of β-Hydroxyketones with Aldolase Antibodies.

High enantiomeric enrichment after 50% conversion: Racemates of aldols can be resolved by the title reaction [Eq.(1)] by use of the aldolase antibody 38C2 or 33F12; the ee values of the unconverted aldols are greater than 95% in most cases. Since the antibodies also catalyze the aldol reaction-that is, the reverse reaction-it is possible to prepare both enantiomers using the same antibody catalysts.