In memory of Prof. Jürgen Sauer
Abstract
There has been increasing interest in the use of tetrazines as partners in bioorthogonal
inverse Diels–Alder cycloadditions. Although tetrazine cycloadditions possess several
characteristics that make them attractive compared to alternative coupling strategies,
the coupling partners, 1,2,4,5-tetrazines and strained alkenes and cycloalkynes, are
not trivial to synthesize. The use of tetrazines and dienophiles in biological applications
has required the development of new synthetic methodologies to create stable yet reactive
probes conveniently. This paper addresses the synthetic milestones that have enabled
and improved tetrazine cycloadditions as a popular form of bioorthogonal chemistry
and highlights recent work from our lab that we believe has advanced the methodology
available for the synthesis of tetrazines[
1
] and smaller strained cyclopropene dienophiles.[
2
] We also outline some future challenges and open questions that remain to be addressed.
Key words
cycloaddition - Diels–Alder reaction - bioorganic chemistry - self-assembly - coupling