Be squared: Expanding the horizon of squaric acid-mediated conjugations

Frederik R. Wurm*, Harm Anton Klok

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

112 Citations (Scopus)


Squaric acid diesters can be applied as reagents to couple two amino-functional compounds. Consecutive coupling of two amines allows the synthesis of asymmetric squaric acid bisamides with either low molecular weight compounds but also biomolecules or polymers. The key feature of the squaric acid diester mediated coupling is the reduced reactivity of the resulting ester-amide after the first amidation step of the diester. This allows the sequential amidation and generation of asymmetric squaramides with high selectivity and in high yields. This article gives an overview of the well-established squaric acid diester mediated coupling reactions for glycoconjugates and presents recent advances that aim to expand this very versatile reaction protocol to the modification of peptides and proteins.

Original languageEnglish
Pages (from-to)8220-8236
Number of pages17
JournalChemical Society reviews
Issue number21
Publication statusPublished - 7 Oct 2013
Externally publishedYes


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