Abstract
A facile and efficient one-pot synthesis of bench-stable quinoxaline N-oxides has been realized using α-oxoketene N,S-acetals and tert-butyl nitrite (TBN) in open air via cascade annulation. The double functionalization of N,S-acetals proceeds through an unanticipated (Csp2)–H nitrosation by NO radical (generated in situ by TBN) and subsequent intramolecular N-arylation leading to quinoxaline, which undergoes oxidation to quinoxaline N-oxides harboring three variegated substituents on their framework. Notably, two new C–N bonds are formed with the same N-oxide nitrogen. This protocol features short reaction time, good functional group tolerance and mild conditions, and does not require the use of either catalyst or external additive.
Key words
ketene
N,
S-acetals -
tert-butyl nitrite (TBN) - radical coupling - quinoxaline
N-oxides
