Divergent Synthesis of 6- or 7-Aza-Indazoles via Intramolecular Diels–Alder Cascade of Pyrazines
Résumé
Pyrazines are reactive 4π partners in intermolecular Diels–Alder cycloaddition with exceptionally activated dienophiles or in an intermolecular version at elevated temperatures. Herein, it is shown that an intramolecular cascade could occur even at room temperature, delivering a collection of 6- or 7-aza-indazoles. An interesting substituent effect of the cycloaddition precursor on the product distribution was uncovered, and in situ NMR studies were conducted to gain insights into this unexpected selectivity.
Domaines
Chimie
Origine : Fichiers produits par l'(les) auteur(s)