TBAF‐Catalyzed Tandem Synthesis of Triazolo[4,5‐ c ]quinolines at Ambient Temperature

Sequential condensation/biannulation reactions of β-(2-aminophenyl)-α,β-ynones with 1,3-dicarbonyls

A divergent domino condensation/biannulation reaction of β-(2-aminophenyl) α,β-ynones with 1,3-dicarbonyls to construct a polycyclic 4H-pyrano[3,4-c]quinoline core has been developed. The p-TsOH·H2O catalyzed reaction of β-(2-aminophenyl) α,β-ynones with β-ketoesters in ethanol proceeds with good to excellent yields to provide a simple and effective method for the synthesis of functionalized 4H-pyrano[3,4-c]quinolinones. Further elaboration of these latter derivatives with an excess of 20% NH4OH in EtOH at 50 °C helps achieve the synthesis of the perlodinine analogues benzo[c][2,7]naphthyridin-4(3H)-one derivatives in high yields. Moreover, the p-TsOH·H2O mediated reaction of β-(2-aminophenyl) α,β-ynones with β-di-ketones leads to the formation of a variety of structurally diverse 4H-pyrano[3,4-c]quinoline polycyclic ketals by the incorporation of an alcohol solvent molecule in a cascade fashion.

Synthesis of quinolines via sequential addition and I2-mediated desulfurative cyclization

An efficient one-pot approach for the synthesis of quinolines from o-aminothiophenol and 1,3-ynone under mild conditions is disclosed. With the aid of ESI-MS analysis and parallel experiments, a three-step mechanism is proposed—a two-step Michael addition–cyclization condensation step leading to intermediate 1,5-benzothiazepine catalyzed by zirconocene amino acid complex Cp₂Zr(η¹-C₉H₁₀NO₂)₂, followed by I₂-mediated desulfurative step.

An efficient one-pot approach is proposed for the synthesis of quinolines through Lewis acid-catalyzed cyclization and iodine-mediated desulfurization reactions.