Science of Synthesis

Slomka, C.; Engel, U.; Syldatk, C.; Rudat, J., Science of Synthesis: Biocatalysis in Organic Synthesis, (2015) 1, 391.

Chemical racemization of 5-monosubstituted hydantoins occurs independently of their enantioselective hydrolysis. The rate is influenced by the electronic nature of the residue at the 5-position and is rather slow for most hydantoins (see Section ‌1.4.5.1.3‌).[‌29‌] d,l-5-(4-Hydroxyphenyl)hydantoin (d,l-‌8‌) possesses one of the highest chemical racemization velocities compared to other hydantoin derivatives, thus allowing the production of d-4-hydroxyphenylglycine (d-‌10‌) with high yield and enantioselectivity. d-4-Hydroxyphenylglycine (d-‌10‌) is of commercial interest and it is used for the production of semisynthetic β-lactam antibiotics. Nevertheless, the production of d-amino acids from d,l-5-monosubstituted hydantoins with a slow chemical racemization rate is also of industrial interest. To avoid the problem of slow racemization, hydantoin racemases can be applied.

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References