Abstract
N-Tosylhydrazones are highly versatile precursors for in situ carbene formation and are frequently used in metal-catalyzed cross-coupling reactions.
Due to their many applications in organic synthesis, including C–C, C–O, C–N, and
C–S bond formation, N-tosylhydrazones have recently received much interest. They can be simply synthesized
by reacting an aldehyde or ketone with N-tosylhydrazine to produce a solid N-tosylhydrazone, which is a ‘green’ precursor of diazo compounds. Using a suitable
metal catalyst, N-tosylhydrazones show versatile substrate scope for the synthesis of substituted diaminopyrroles,
chromenopyrazoles, alkenylpyrazoles, benzofuran thioethers, tetrahydropyridazines,
sulfur-containing heterocycles, and benzofurans with potent biological activities
and even regioselective N-functionalization reactions. Metal-catalyzed reactions of N-tosylhydrazones for the construction of bioactive heterocycles are still highly in
demand. Hence, this review focuses on the recent synthetic application of N-tosylhydrazones influenced by different transition metals with notable features like
simple workup procedures, gram-scale synthesis, broad substrate scope, multicomponent
processes, cyclization, and carbon–heteroatom bond formation.
1 Introduction
2 Applications of N-Tosylhydrazones
3 Conclusion
Key words
N-tosylhydrazone - cross-coupling reaction - regioselective - carbene - cycloaddition
- olefination
