Synthesis of hexahydroquinoline (HHQ) derivatives using ZrOCl₂·8H₂O as a potential green catalyst and optimization of reaction conditions using design of experiment (DOE)

Abstract

In this investigation, hexahydroquinoline (HHQ) derivatives were synthesized via a one-pot reaction using dimedone, β-ketoester, ammonium acetate, and different aryl aldehydes.

Magnetic‐based picolinaldehyde–melamine copper complex for the one‐pot synthesis of hexahydroquinolines via Hantzsch four‐component reactions

“…The conventional method which is used by many chemists is ‘change one variable at a time’ (OVAT) or interchangeably ‘one factor at a time’. If the is a considerable interaction between parameters the OVAT procedure is not efficient, so that it gives an unrealistic optimal point . The large number of experiments is another relevant feature of this method, so it is not efficient from material, time and economic points of view .…”

“…As shown, and based on IR investigations, the as‐prepared catalyst interacts only with benzaldehyde and reduces the carbonyl band wavenumber from 1703.92 to 1687.49 cm −1 . The details of the mechanism, along with the associated intermediates, are presented in the literature …”

“…If the is a considerable interaction between parameters the OVAT procedure is not efficient, so that it gives an unrealistic optimal point. [29,45,46] The large number of experiments is another relevant feature of this method, so it is not efficient from material, time and economic points of view. [47,48] Unfortunately, many researchers probes their optimal conditions through OVAT methodology.…”

“…The details of the mechanism, along with the associated intermediates, are presented in the literature. [29,54] 4 | CONCLUSIONS In summary, a magnetic-based picolinaldehydemelamine copper complex was synthesized and used in the synthesis of HHQ derivatives. The synthesized catalyst contains 0.33 mmol of Cu per gram which can activate the reaction between starting materials.…”

“…Synthesis of novel HHQ derivatives via efficient approaches and evaluation of the pharmacological properties are the main aims of the research. Considering the above discussion, various catalysts such as γ‐Fe 2 O 3 , SBA‐15/SO 3 H nanoreactor, KH 2 PO 4 , sulfamic acid‐functionalized nano‐titanium dioxide, nano‐CoAl 2 O 4 , nano‐ZrO 2 ‐SO 3 H, ZrOCl 2 ⋅8H 2 O, silica‐bonded imidazolium–sulfonic acid chloride, nano‐Fe 3 O 4 –TiO 2 –SO 3 H, 1,3‐disulfonic acid imidazolium hydrogen sulfate, amino alcohol, basic isoreticular metal–organic framework (IRMOF‐3), SBA‐SO 3 H, [MPIm][HSO 4 ]@SBA‐15, SBA‐15/NHSO 3 H and ionic liquids grafted onto graphene oxide have been used in the synthesis of HHQs and DHPs. Although impressive successes have been achieved, most of the developed catalysts suffer from long reaction time (half an hour to several hours), and not so simple procedures for separation of the catalyst.…”