Reductive amination in nature
المؤلف:
Jonathan Clayden , Nick Greeves , Stuart Warren
المصدر:
ORGANIC CHEMISTRY
الجزء والصفحة:
ص1150-1151
2025-08-14
452
Reductive amination in nature
One of the best methods for making amines in the laboratory is reductive amination, in which an imine (formed from a carbonyl compound and an amine) is reduced to a saturated amine. Common reducing agents include NaCNBH3 and hydrogen with a catalyst.
This reaction, of course, produces racemic amines. But nature transforms this simple reaction into an enantioselective and reversible one that is beautiful in its simplicity. The reagents are a pair of substituted pyridines called pyridoxamine and pyridoxal, and the enzyme is an aminotransferase.
The mechanism of the amination starts with the formation of an imine from the black amino group and the green carbonyl. Removal of the now very acidic proton between the protonated pyridine and the conjugated imino-carboxylic acid gives a dihydropyridine, which rearomatizes by protonation next to the carboxylic acid. This step is enantioselective, with the proton being delivered from the enzyme. Finally, hydrolysis of the new imine gives pyridoxal and a single enantiomer of the amino acid.
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