Primary amine catalysis

In enzymic decarboxylations the mechanistic pathway seems to involve Schiff base formation between an —NH2 from a lysine residue and a C=0 of the keto acid.52 Likewise, with small-molecule primary amines, catalysis of decarboxylation of /3-ketoacids53-58 has been ascribed to a Schiff base intermediate. The overall reaction for oxalacetate is... 

In contrast to primary amine catalysis, the enamine mechanism has been ruled out for D—H exchange in isobutyraldehyde catalysed by secondary amines. Catalytic rate constants were explained by considering only the... 

Primary amine catalysis (usually involving a lysine residue) has been recognised to play an important role in various enzyme-catalysed reactions. Examples are the conversion of acetoacetate to acetone catalysed by acetoacetate decarboxylase, the condensation of two molecules of S-aminolevulinic acid catalysed by -aminolevulinic deshydratase during the biosynthesis of porphyrins, and the reversible aldol condensation of dihydroxy-acetone phosphate with glyceraldehyde which in the presence of aldolase yields fructose-1-phosphate (64) (For reviews see, for example, Snell and Di Mari,... 

Important parameters for understanding the efficiency of primary amine catalysis are the ketone + amine to enamine equilibrium constants. Unfortunately, data are very scarce. Equilibrium constants for the interconversion (65) of [2H6]acetone and protonated enamine in water ( H =... 

The analogy between primary amine catalysis and some enzyme-catalysed biochemical processes has been stressed. There is not doubt that further studies of amine catalysis would help in understanding enzyme catalysis via organic... 

Cinchona-based primary amine catalysis in the asymmetric functionalization of carbonyl compounds 12AG(E)9748. 

Cinchona-based primary amine catalysis in the asymmetric functionalization of carbonyl compounds has been reviewed and their modularly designed thioamide 0 derivatives have been applied successfully to direct cross-aldol reactions between aldehydes and ketones, reactions of activated carbonyl compounds (isatins) with acetylphosphonate as the enol precursor, and C( 1) functionalization of 1,3-dicarbonyl compounds by aldehydes and ketones. Cross-aldol addition to C(3) of isatins by the methyl group of 4-aryl-tra 5 -cf, -unsaturated methyl ketones has also been promoted... 

In the blossom of organocatalysis, the development with primary amine catalysts has been rather slow and largely neglected prior to 2005 despite of the remarkable successes with secondary aminocatalyts [ 1 ]. This fact is mainly ascribed to the relatively stabilized imine/iminium intermediate (I) and the assumed unfavorable iminium (I)-enamine (II) transformation in primary amine catalysis (Scheme 5.1). In fact. 

Enamine-Based Chiral Primary Amine Catalysis 5.2.1 Aldol Reaction... 

Aldol reaction is well known to be an intrinsically reversible process. Microscopically, asymmetric retro aldol reaction would address those challenging substrates which are normally sluggish under the typical asymmetric aldol conditions. Unfortunately, though principally conceivable, such asymmetric retro aldol processes remain basically underdeveloped in asymmetric synthesis. In their further explorations on chiral primary amine catalysis, Luo group found that simple chiral primary-tertiary diamine such as 24,26,27,29, 33 catalyze unprecedentedly stereoselective retro aldol reactions (Scheme 5.13). 

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