Some derivatives of benz[f]azepine. Part III

Abstract

We report the synthesis by two routes, of hitherto unknown 3, 4‐epoxy‐2, 3, 4, 5‐tetrahydrobenz[f]azepine‐2, 5‐dione and hence a new route to 2, 3, 4, 5‐tetrahydrobenz[f]azepine‐2, 4, 5‐triones which are precursors of 2‐quin‐olonecarboxylic acids.

Synthesis of Oxazole Analogs of Streptolidine Lactam

“…The oxidation of 11* by treatment with dichromate furnished meso ‐diketoepoxide 12 , which was the precursor for the subsequent ring‐expansion reaction. Guided by literature precedent for the conversion of an epoxy naphthoquinone into a benzazepine,14 we applied the Schmidt reaction to the ring expansion of 12 to give epoxy ketolactam 13* , and the stereochemistry of 13* was confirmed by crystal structure analysis. The optimization of the conditions for the Schmidt reaction of 12 led us to introduce glacial acetic acid as a solvent, which allowed for better control of the heat generation and dissipation as well as prevented charring during the addition of the azide.…”

“…rac ‐8‐Oxa‐3‐azabicyclo[5.1.0]octane‐2,6‐dione (13*): 14,17 To a solution of 7‐oxabicyclo[4.1.0]heptane‐2,5‐dione ( 12 , 0.39 g, 3.08 mmol) in water (2.0 mL) and glacial acetic acid (4.05 mL) was added sodium azide (0.50 g, 7.71 mmol) with vigorously stirring, and then the reaction mixture was cooled to 5 °C. Ice‐cold concentrated sulfuric acid (7 mL) was added at a rate of 4 drops per minute, and the evolution of nitrogen was observed.…”

Gold or No Gold: One-Pot Synthesis of Tetrahydrobenz[b]azepin-4-ones from Tertiary N-(But-3-ynyl)anilines

“…Intermolecular 1,3-dipolar cycloaddition between C , N -diphenylnitrone and allenes followed by in situ rearrangement offers rapid access to these structures but suffers from limited scope, rather rigid product substitution patterns, and low yields . Other less studied approaches include intramolecular anionic cyclization of N -aryl β-lactams and ring expansion via the Schmidt reaction . In our opinion, there is still a need for methods that offer synthetic flexibility and efficiency and proceed under mild reaction conditions.…”