Bovine and human serum albumins catalyze the aldol reaction of aromatic aldehyedes and acetone, with saturation kinetics and moderate and opposite enantioselectivity. The reaction occurs at the binding site in domain IIa, and is inhibited by warfarin. Kinetic data are consistent with an enamine mechanism. The activity is conserved in a 103 aminoacid peptide derived from the albumin sequence.

We describe herein an unprecedented asymmetric α-amination of β-ketocarbonyls under aerobic conditions. The process is enabled by a simple chiral primary amine through the coupling of a catalytic enamine ester intermediate and a nitrosocarbonyl (generated in situ) derived from N-hydroxycarbamate. The reaction features high chemoselectivity and excellent enantioselectivity for a broad range of s...

A Diels-Alder reaction between cyclopentadiene and a variety of ketenimines is reported. A copper(I)-bis(phosphine complex catalyzes the cycloaddition across the C═N bond of the ketenimine in a [4 + 2] reaction to give an enamine intermediate that is hydrolyzed upon purification to generate aminoketones.

[reaction: see text] Benzaldehyde lyase from the Pseudomonas fluorescens catalyzes the reaction of aromatic aldehydes with methoxy and dimethoxy acetaldehyde and furnishes (R)-2-hydroxy-3-methoxy-1-arylpropan-1-one and (R)-2-hydroxy-3,3-dimethoxy-1-arylpropan-1-one in high yields and enantiomeric excess via acyloin linkage. Aromatic aldehydes and benzoins are converted into enamine-carbanion-li...

In the title compound, C(21)H(21)N(3)O(2), an intra-molecular N-H⋯O inter-action generates an S(6) ring, which stablizes the enamine-keto tautomer. The S(6) ring makes dihedral angles of 33.07 (7), 56.50 (8) and 38.59 (8)°, respectively, with the benzoyl-acetone benzene ring and the anti-pyrine pyrazole and benzene rings.

The title compound, C(18)H(27)NO(2), crystallizes as the enamine form with Z geometry. The β-enamino-ester fragment forms a dihedral angle of 87.5 (1)° with the isopropyl-phenyl frame. The structure exhibits an intra-molecular N-H⋯O hydrogen bond. In addition, in the crystal, mol-ecules are linked by a centrosymmetric inter-molecular N-H⋯O hydrogen bond.

The approach using pyrrolidine enamine as substrate has been studied for this synthesis, and an important catalyst structural feature has been developed. After survey of pyrrolidine-based Brønsted acid catalyst, tetrazole catalyst (3f) was found to be optimal in synthesis of aminooxy carbonyl compounds in high yields, with complete enantioselectivity not only for aldehydes but also for ketones.

Copper-catalyzed cyclization of an oxime ester toward divergent heterocycle synthesis is reported. Oxime ester serves as an enamine precursor to cyclize with malononitrile and aldehydes for access to 2-aminonicotinonitriles in a one-pot reaction, while cyclizing with N-sulfonylimines leads to synthesis of pyrazolines.