Rhodium(III)-Catalyzed Redox-Neutral [3+3] Annulation of N-nitrosoanilines with Cyclopropenones: A Traceless Approach to Quinolin-4(1H)-One Scaffolds

Abstract

A traceless approach to quinolin-4(1H)-one scaffolds through Rh(III)-catalyzed redox-neutral [3+3] cyclization of N-nitrosoanilines with cyclopropenones has been achieved. This protocol features short reaction time and atom-economical combination without extra additives, which can be further applied in the construction of privileged heterocyclic compounds in pharmaceutical chemistry.

N‐Nitroso As A Novel Directing Group in Transition‐Metal‐Catalyzed C(sp2)−H Bond Functionalizations of N‐Nitrosoanilines

“…Concurrently, the same 4‐quinolone scaffold was also obtained by Zhou and Liu and co‐workers as an [3+3] annulation product of N ‐nitrosoaniline and cyclopropenone when the reaction was conducted in a mixture of 10 mol% Rh(III) and 1 eq. AgBF 4 in DCE at 100 °C (Scheme 25, Condition B) [58] . In comparison with the previous protocol, this cycloaddition effectively proceeds without any additive to generate 4‐quinolone derivatives with broad substrate scope.…”

“…AgBF 4 in DCE at 100 °C (Scheme 25, Condition B). [58] In comparison with the previous protocol, this cycloaddition effectively proceeds without any additive to generate 4-quinolone derivatives with broad substrate scope. The orthoproton elimination is irreversible which occurs at the ratedetermining step with k H /k D = 1.7.…”

Novel Two-Step Synthesis of N-Alkylated 2,3-Diaryl-4-quinolones

“…Eluent for chromatographic purification: EtOAc/PE (1:2); yield: 66 mg (0.167 mmol, 67%); light yellow powder; mp 261-263 °C (EtOH); R f = 0.32 (EtOAc/PE 1:1 40 Eluent for chromatographic purification: EtOAc/PE (1:2); yield: 39 mg (0.12 mmol, 48%); light yellow powder; mp 275-276 °C (EtOH); R f = 0.35 (EtOAc/PE 1:1). FTIR (KBr): 3091, 3082, 1656, 1587, 1561, 1522, 1463, 1379, 1333, 783 cm -1 .…”

Heterocycles from cyclopropenones

“…The rhodium-catalyzed reaction occurred between substituted N -nitrosoanilines 60 and 1b in the presence of AgBF 4 and DCE at 100 °C for 12 h. The quinoline-4-one derivatives 93a–f were produced in 46–70% yield, as shown in Scheme 58. 102…”