1-(7-Chloro-1,4-dihydroquinolin-4-ylidene)thiosemicarbazide and its hydrochloride: evidence for the existence of a stable imine tautomer in the solid state of 4-aminoquinoline free bases, an anomalous case in nitrogen heterocycles

Abstract

In the solid state, crystals of both 1-(7-chloro-1,4-dihydroquinolin-4-ylidene)thiosemicarbazide-methanol-water (2/1/1), 2C10H9ClN4S·CH3OH·H2O, (I), and its hydrochloride salt {systematic name: [(7-chloro-1,4-dihydroquinolin-4-ylidene)azaniumyl]thiourea chloride}, C10H10ClN4S(+)·Cl(-), (II), assume the imine tautomeric form, contrary to other 4-amino-7-chloroquinolines. Of particular interest are the N-C bond lengths, which have appreciable double-bond character, and the C-N-C aromatic ring bond angle. Both of these parameters have been studied extensively in 4-amino-substituted quinolines. The crystal structures of (I) and (II) in this study provide interesting examples of the amino-imino tautomerism which exists in this class of compound and is, to the best of our knowledge, hitherto unreported.

Antileishmanial Activity, Cytotoxicity and Mechanism of Action of Clioquinol Against Leishmania infantum and Leishmania amazonensis Species

“…The ROS production in L. amazonensis promastigotes was evaluated in the treated parasites, as described in . Briefly, promastigotes (1 × 10 7 cells) were incubated alone or with clioquinol (2.55 and 5.10 μg/mL) for 6 hr at 25°C.…”

Click synthesis of new 7-chloroquinoline derivatives by using ultrasound irradiation and evaluation of their biological activity

“…The application of ultrasound in the synthesis of compounds (2) and 3is fulfilling some of the goals of "green and sustainable chemistry" as it has some advantages comparing with the traditional thermal methods in terms of reaction times, yields and purity of the products (16,17). The reaction of 4,7-dichloroquinoline and o-phenylenediamine in the presence of ethanol under reflux in an ultrasonic bath, for 30 min at 90°C yielded N-(7-chloroquinolin-4-yl)-benzene-1,2-diamine (2) (cf.…”