Green and efficient three-component synthesis of 4H-pyran catalysed by CuFe2O4@starch as a magnetically recyclable bionanocatalyst

The development of simple, practical and inexpensive catalysis systems using natural materials is one of the main goals of pharmaceutical chemistry as well as green chemistry. Owing to the ability of easy separation of nanocatalyst, those goals could be approached by applying heterogeneous bionanocatalyst in combination with magnetic nanoparticles. Starch is one of the most abundant natural polymers; therefore, preparing bionanocatalyst from starch is very valuable as starch is largely available and inexpensive. An ecologically benign and efficacious heterogeneous nanocatalyst was prepared based on a biopolymer, and its attributes and morphology were specified by using Fourier transform infrared spectra, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermal analysis and vibrating sample magnetometer measurements; followed by studying catalytic behaviour of bionanocomposite in a multicomponent reaction to synthesize of 4H-pyran derivatives. 4H-pyran is extremely valuable in pharmaceutical chemistry, and the development of methods for synthesis of different derivatives of 4H-pyran is momentous. Revealing environmentally benign nature, mild condition, easy work-up, low cost and non-toxicity are some of the advantages of this protocol. Besides, the bionanocomposite was recovered using an external magnetic bar and could be re-used at least six times with no further decrease in its catalytic activity.


Comments to the Author(s)
In this work, the authors reported on the synthesis of heterogeneous nanocatalyst based on a biopolymer followed by multicomponent reaction for the synthesis of 4H-pyran derivatives. The idea is interesting and off added value to researchers in the field of nano materials, however some flaws have been observed in the manuscript that i can outline as follow: -English is poor and needs professional editing.
-Abstract should be modified to be more informative.
-Introduction failed to show the novelty of the current work in relation to previous publications. -conclusion should be different than abstract and includes the optimum conditions for the obtained results.
-References are too many for an article, also ref 37 is not consistent with the style. I recommend major revision Review form: Reviewer 2

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? No

Recommendation?
Accept with minor revision (please list in comments)

Comments to the Author(s)
In this manuscript authors have used starch as a biocompatible solid support to design magnetic nanobiocatalyst for three component coupling reaction for the synthesis of 4H-pyran derivatives. Utilization of bio support and magnetic separation are the advantages of this work. But several useful information are not provided in this manuscript. Thus, I recommend this manuscript for publication after a revision addressing the comments given below: Introduction is not written properly. Several other catalysts which can catalyze this three component coupling reactions involving activated aromatic compounds, aromatic aldehyde and malononitrile should be referred. See and include : Dalton Trans., 2013, 42, 10515-10524;RSC Adv., 2012, 2, 11306-11317. Electron microscopic image as presented in Figure 3 is of very low resolution. It is very hard to understand the particle size and shape from this image. Better quality image should be provided.
In the powder XRD pattern shown in Figure 4, peaks corresponding to the CuFe2O4 phase should be indexed.
Powder XRD pattern of the used CuFe2O4@starch catalyst after six reaction cycles should be provided.
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-Abstract should be modified to be more informative. Electron microscopic image as presented in Figure 3 is of very low resolution. It is very hard to understand the particle size and shape from this image. Better quality image should be provided.
In the powder XRD pattern shown in Figure 4, peaks corresponding to the CuFe2O4 phase should be indexed.
Powder XRD pattern of the used CuFe2O4@starch catalyst after six reaction cycles should be provided.
Thorough English language editing is needed.

Author's Response to Decision Letter for (RSOS-200385.R0)
See Appendix A.

Decision letter (RSOS-200385.R1)
We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below. Thank you so much for your kind e-mail message on April 15, 2020; and very useful Reviewers' comments and editorial suggestions on our manuscript (ID: RSOS-200385). It is our great pleasure to submit the enclosed revised manuscript to be considered for publication in the Royal Society Open Science. We have modified the manuscript accordingly (as highlighted by the yellow color in Text), and detailed corrections are listed point by point as follows: *********************************************

-Reviewer 1
In this work, the authors reported on the synthesis of heterogeneous nanocatalyst based on a biopolymer followed by multicomponent reaction for the synthesis of 4H-pyran derivatives. The idea is interesting and off added value to researchers in the field of nano materials, however some flaws have been observed in the manuscript that I can outline as follow: -English is poor and needs professional editing.
Answer: We greatly appreciate your careful reading and reviewing our manuscript. The whole Text was edited by an official English translator.
-Abstract should be modified to be more informative.
Answer: Thank you for your comment. It was done in the main manuscript in the abstract section.
-Introduction failed to show the novelty of the current work in relation to previous publications.
Answer: Thank you for your insightful comment. It was done in the main manuscript in the introduction section.
Appendix A -Conclusion should be different than abstract and includes the optimum conditions for the obtained results.
Answer: Thank you for your comment. It was done in the main manuscript in the conclusion section.
-References are too many for an article, also ref 37 is not consistent with the style.
Answer: Thank you for your comment. The number of references was decreased as much as possible.

Reviewer 2
In this manuscript authors have used starch as a biocompatible solid support to design magnetic nanobiocatalyst for three component coupling reaction for the synthesis of 4H-pyran derivatives.
Utilization of bio support and magnetic separation are the advantages of this work. But several useful information are not provided in this manuscript. Thus, I recommend this manuscript for publication after a revision addressing the comments given below: Answer: Thank you for your comment. Sure, they are worthy reports and were used in the introduction section.
-Electron microscopic image as presented in Figure 3 is of very low resolution. It is very hard to understand the particle size and shape from this image. Better quality image should be provided.
Answer: Thank you for your comment. The Electron microscopic image of bionanocatalyst was replaced (Figure 3).
-In the powder XRD pattern shown in Figure 4, peaks corresponding to the CuFe2O4 phase should be indexed.
Answer: Thanks for your admirable attention. The indices of the peaks were shown in XRD patterns (Figure 4).
-Powder XRD pattern of the used CuFe2O4@starch catalyst after six reaction cycles should be provided.
Answer: Thank you for your comment. The powder XRD pattern of the reused catalyst was added in the main manuscript (Figure 4).
-Thorough English language editing is needed.
Answer: Thank you for your comment. The whole Text was edited by an official English translator.