Dedicated to Prof. Mikhail S. Novikov on the occasion of his 60th birthday and to Prof. Alexander F. Khlebnikov on the occasion of his 70th birthday
Abstract
Diazo compounds display versatile reactivity and therefore are widely used in organic synthesis. Diazo compounds bearing a 2-pyridyl or a related azine moiety on the diazo carbon exist in the form of fused 1,2,3-triazoles. In this short review, we summarize the recent advances in denitrogenative reactions of [1,2,3]triazolo[1,5-a ]pyridines (‘pyridotriazoles’) and related fused 1,2,3-triazoles. Over the past decade, there has been a surge of activity in this field, with novel denitrogenative reactions of pyridotriazoles induced by metal compounds, light, and Brønsted and Lewis acids having been devised. As a result, heterocyclic compounds and functionalized α-picolines as well as bioactive molecules have been synthesized. In the review, emphasis is also placed on the mechanisms of the new reactions.
1 Introduction
2 Ring-Chain Isomerization of Pyridotriazoles
3 Metal-Catalyzed Reactions
3.1 Rh(II) Catalysis
3.2 Rh(III) Catalysis
3.3 Cu Catalysis
3.4 Pd Catalysis
3.5 Catalysis by Other Metals
4 Metal-Free Reactions
5 Conclusion
Key words pyridotriazoles - 1,2,3-triazoles - diazo compounds - carbenes - catalysis - nitrogen heterocycles - α-picolines
