Abstract
Phosphorus-containing N-heterocycles are important molecular motifs due to their unique
structural features and biological activities. In this study, we developed a silver-catalyzed
reaction for the construction of phosphorus-containing azepine derivatives via a domino-type
dearomatization procedure, followed by ring expansion. In addition, diazomethylphosphonates
were employed for the first time as nucleophiles in the 1,4-dearomative addition of
activated N-heteroarenes, furnishing cyclopropane-fused piperidine intermediates that
were readily restructured into their corresponding azepine derivatives. The reactivities
of the diazomethylphosphonates in the developed dearomatization strategy were found
to be superior to those of other diazo compounds, thereby resulting in the generation
of the desired seven-membered N-heterocycles within a very short reaction time.
Key words
heterocyclic compound - silver catalyst - ring expansion - dearomatization - diazomethylphosphonate
- N-aromatic zwitterion
