A highly selective and easy-to-synthesize Zn(II) fluorescent probe based on 6-methoxyquinolin

Oxalylacetylenes as Dielectrophiles for Annulation of Quinoline Rings: Synthesis of Highly Functionalized 1,3-Oxazinoquinolines

Oxalylacetylenes act as dielectrophiles in the annulation of quinolines to give highly functionalized 1,3-oxazine cycles decorated with ethynyl, oxalyl, ester and aryl substituents. The annulation proceeds under mild conditions (room temperature, without catalyst) in 2:1 mode with respect to acetylene and quinoline to deliver 1,3-oxazinoquinolines in 45–88% yields. A beneficial feature of the reaction is that, in contrast to results on the reaction of quinolines with trifluoroacetylacetylenes in the presence of water, where H2O acted as a third electrophile, leading to the 1,3-oxazinoquinolines containing a hydroxyl group, this reaction well tolerates the aqueous medium. This reaction also tolerates isoquinoline and phenanthridine.

Cyanoquinolines and Furo[3,4-b]quinolinones Formation via On-The-Spot 2,3-Functionalization of Quinolines with Cyanopropargylic Alcohols

A convenient approach to 2-(1-ethoxyalkoxy)-3-cyanoquinolines (in up to 50% yields) has been developed. The approach comprises functionalization of quinolines with acetals of cyanopropargylic alcohols (KOH/H₂O/MeCN, 55-60 °C) followed by their transformation to furo[3,4-b]quinolinones (in up to 98% yields) via the sequential removal of acetal protection and intramolecular cyclization/hydration (7% aqueous HCl, acetone, 20-25 °C).

Cyanoacetylenes as Triggers and Partners in KOH-Assisted Assemblies of Quinoline-Based Dihydropyrimido[1,2-a]quinolin-3-ones on Water

Arylcyanoacetylenes trigger the assembly of dihydropyrimido[1,2-a]quinolin-3-ones in good to excellent yields on the platform of quinolines in the presence of KOH in aqueous media at room temperature. This green on-water methodology provides a simple one-pot access to a novel family of the pharmaceutically prospective compounds.

A novel quinoline-based two-photon fluorescent probe for detecting Cd2+ in vitro and in vivo

A new two-photon fluorescent Cd(2+) probe APQ is developed by introducing a N(1),N(1)-dimethyl-N(2)-(pyridin-2-ylmethyl)ethane-1,2-diamine binding group and a 4-methoxyphenylvinyl conjugation-enhancing group to the 2- and 6-positions of quinoline. This probe shows a large red shift and good emission enhancement under Cd(2+) binding. It also exhibits a high ion selectivity for Cd(2+) (especially over Zn(2+)) and a large two-photon absorption cross section at 710 nm. Two-photon microscopy imaging studies reveal that the new probe is non-toxic and cell-permeable and can be used to detect intracellular Cd(2+) under two-photon excitation.