An Amino-Chain Modified β-cyclodextrin: A Supramolecular Ligand for Pd(OAc)2 Acceleration in Suzuki–Miyaura Coupling Reactions in Water

Round 1

Reviewer 1 Report

In this manuscript, the authors report a new catalyst for the Suzuki–Miyaura cross‐coupling reaction in water. The catalyst was a palladium salt stabilized by an ethylene diamino  modified β-cyclodextrin. This complex is active and can be recovered. A mechanism based on NMR, FTIR, FE-SEM, and DSC experiments was also described. This manuscript is well written and the conclusions are well supported by experimental data. As this catalyst is very simple to synthesize and active, I think that this manuscript could interest numerous researchers. I recommend the publication of this manuscript  after minor corrections. (i) The reactivity of chlorobenzene derivatives is not reported in this manuscript. What is the reactivity of the catalyst towards such deactivated substrates? (ii) A weak decrease in the catalytic activity was observed during the recycling. The authors should comment this point. (iii) following references concerning the Suzuki–Miyaura cross‐coupling reaction in water with phosphine free CD ligands have not been mentioned and should be added in the references part : Org. Lett. 2006, 8, 4823-4826 DOI: 10.1021/ol061836v; Appl. Organometal. Chem. 2017;31:e3592,  doi.org/10.1002/aoc.3592 ; New J. Chem. 2011, 35, 2061-2065, DOI: 10.1039/c1nj20200f

Author Response

Response to Reviewer 1 Comments

In this manuscript, the authors report a new catalyst for the Suzuki–Miyaura cross‐coupling reaction in water. The catalyst was a palladium salt stabilized by an ethylene diamino modified β-cyclodextrin. This complex is active and can be recovered. A mechanism based on NMR, FTIR, FE-SEM, and DSC experiments was also described. This manuscript is well written, and the conclusions are well supported by experimental data. As this catalyst is very simple to synthesize and active, I think that this manuscript could interest numerous researchers. I recommend the publication of this manuscript after minor corrections. Here, I listed some comments and points to be revised. 

Point 1: The reactivity of chlorobenzene derivatives is not reported in this manuscript. What is the reactivity of the catalyst towards such deactivated substrates?

Response 1: As your suggestion, in order to determine the effect of catalyst (PdLn@Et-β-CD) towards deactivated substrates such as chlorobenzene derivatives, we carried out one reaction with 1-chloro-4-nitrobenzene a moderate yield (54%) were obtained when aryl chloride were used and obtained result are included in revised manuscript.

Point 2: A weak decrease in the catalytic activity was observed during the recycling. The authors should comment this point.

Response 2: In recycling procedure, ethyl acetate was used to separate the organic phase after the completion of each cycle. Then, the aqueous phase was used in the next run without changing the reaction conditions. Actually, we did neither evaporate the aqueous phase nor wash the catalyst by any organic solvent. Moreover, we did not use any extra base for the next reaction cycle, this might be the reason for a weak decrease in the catalytic activity.

Point 3: Following references concerning the Suzuki–Miyaura cross‐coupling reaction in water with phosphine free CD ligands have not been mentioned and should be added in the references part : Org. Lett. 2006, 8, 4823-4826 DOI: 10.1021/ol061836v; Appl. Organometal. Chem. 2017;31:e3592,  doi.org/10.1002/aoc.3592 ; New J. Chem. 2011, 35, 2061-2065, DOI: 10.1039/c1nj20200f

Response 3: As your suggestion, we added your mentioned references in the revised manuscript.

Thank you very much for your helpful comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this article a cyclodextrin-Pd catalyst already used by the authors on Heck reaction is here applied to a Suzuki coupling in water.  The paper here presented is well described, the catalyst is well characterized and both the optimization and the scope of the reaction are coherent with the work which is quite innovative and i consider it suitable for the publication in Catalysts. Few errors should be corrected: in Scheme 1 tosylimidazole is used to functionalize the beta-cyclodextrin but in the text tosylchloride is indicated. In figure 4 the word separation lacks the final "n".

Author Response

Response to Reviewer 2 Comments

In this article a cyclodextrin-Pd catalyst already used by the authors on Heck reaction is here applied to a Suzuki coupling in water.  The paper here presented is well described, the catalyst is well characterized and both the optimization and the scope of the reaction are coherent with the work which is quite innovative and i consider it suitable for the publication in Catalysts. Few errors should be corrected.

Point 1: In Scheme 1 tosylimidazole is used to functionalize the beta-cyclodextrin but in the text tosylchloride is indicated.

Response 1: According to your suggestions, we corrected the mistake in the revised manuscript.

Point 2: In figure 4 the word separation lacks the final "n".

Response 2: As your suggestion, we corrected the word separation in figure 4 in the revised manuscript.

Thank you very much for your helpful comments.

Author Response File: Author Response.pdf