Hydroxy- and aminomethylation reactions in the formation of oligomers from L-tyrosine and formaldehyde in basic medium

The study of the reaction of L-tyrosine or its tetrabutylammonium salt with formaldehyde was performed. The results established that this reaction does not lead to macrocyclic amino acid-type compounds, and in all cases, mixtures of linear oligomers of two or more L-tyrosine units bound by methylene groups were obtained. The formation of ion pair-type linear aggregates in the tetrabutylammonium salt hinders the oligomerization reaction, allowing the isolation of an L-tyrosine dimer, unlike the L-tyrosine reaction, in which a trimer could be isolated. In this Letter, the behavior of different L-tyrosine derivatives with formaldehyde is analyzed, and the conditions that direct the reaction course toward macrocyclic or linear compounds are discussed. (C) 2014 Elsevier Ltd. All rights reserved.