1,2,4,5-Tetrazines

Abstract

This chapter describes the new developments in the field of 1,2,4,5-tetrazine chemistry from 1995 to 2006, with emphasis on theoretical methods, experimental structural methods, synthesis of novel 1,2,4,5-tetrazine derivatives, and applications of 1,2,4,5-tetrazines in organic synthesis. X-Ray diffraction, mass spectrometry, thermodynamic aspects, spectral characteristics, and ring–chain tautomerism are discussed. An overview on the synthesis of fully conjugated, dihydro-, and annelated 1,2,4,5-tetrazines and transformations of fully conjugated systems, such as retention of the ring system, including N-oxidation and redox reactions, and nucleophilic substitution is presented. The section on transformation of the ring system includes [4+1], [4+2], and intramolecular cycloaddition reaction with alkenes, alkynes, enolates, enamines, iminoethers, and amidines as dienophiles. Ring contractions, thermal and photochemical unimolecular reactions, charge-transfer complexes, and applications conclude the chapter.