Synthesis of Xylyl-Linked Bis-Benzimidazolium Salts and Their Application in the Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling Reaction of Aryl Chlorides
Round 1
Reviewer 1 Report
The reviewer comment is attached.
Comments for author File: 
Comments.doc
Author Response
Q1. In Figure 1, authors showed “offers flexibility and electronic effect’’ to explain significance of Ar moiety in bis-benzimidazolium salt 3. However, the reviewer thought conformation of this moiety would be more rigid compared with bis-benzimidazolium salt L. Explain what is flexible in detail. In line 74, authors found xylyl-bridged bis-benzimidazolium precursor 3b showed better activity in comparison to alkyl-linked bisbenzimidazolium salt L. If it is possible, explain what kind of effect in 3b contribute to the improved activity.
Response Q1: The "flexibility" is not meant to compare salt L with salt 3b, but to compare the benzimidazole salts which connected to the aromatic ring directly. Flexibility of the linker is not a key point of our findings. The characteristics of the xylyl-bridged bis-benzimidazolium salts have been described in the revised manuscript. (see revised manuscript: Catalysts-1284776_1)
Q2. It is better to add a scheme of 4a and 5a above Table 1, which would help readers to easily understand the results.
Response Q2: The scheme was added. (see revised manuscript: Catalysts-1284776_1)
Q3. In line 104, the title of Table 2 is not appropriate due to SMC reactions, but not transfer hydrogenation.
Response Q3: The title of Table 2 was revised. (see revised manuscript: Catalysts-1284776_1)
Q4. In Table 3, One concern raised by the reviewer is low chemical yields in SMC reactions of p- and m-chlorotoluene in spite of high yield in that of o-chlorotoluene (Table 3). If it is possible, explain why only o-chlorotoluene functions as a good substrate.
Response Q4: The experiments had been repeated three times, but similar results were obtained. The results demonstrated that the SMC reactions can not go completion when the p-chlorotoluene (4k) and m-chlorotoluene (4l) were used as the starting material. The GC ratio of 4k to 6ka was found to be 76:24 while that of 4l to 6la was 68:32.
Q5. In Scheme 1, correct “2,4,6-Mesyl” into ‘’Mesityl’’. In Scheme 1, correct “Mesyl” into ‘’Mesityl’’. In Scheme 1, correct “refluxed” into ‘’reflux’’. In Table 3, yield of 6ka and 6la, correct “yieldb” into ‘’yield’’.
Response Q5: The mistakes in Scheme 1 had been revised. (see revised manuscript: Catalysts-1284776_1)
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper describes a useful synthetic procedure for preparation of biaryls by Suzuki-Miyaura reaction between chloroarenes and arylboronic acids. The authors found good catalytic system for involvement of chloroarenes in this important transformation. It is a real challenge to conduct this reaction with chloroarenes. Authors did a good contribution in this field. They throughly studied synthetic potential of their catalytic system. They showed a broad scope of the reaction. Authors provide reliable synthetic procedures and complete characterization of the obtained compounds. This paper may be accepted. However, there are some critical points.
- The authors used the term "xylyl" in the paper. However, xylyl, as substituent, is dimethylphenyl group. I am afraid that "xylyl'' has nothing to do with structures 3a-f. The "xylyl"term is incorrect in this paper. It is a laboratiry slang! Better to use another term for a discription of structures 3.
- Page 2, lines 61-65: the description of spectral data is not necessarily! These data a given in Experimental Part and SI.
- Page 4, entry 1 in Table 1: What is L? It is not clear.
After these corrections, the paper may be accepted.
Author Response
Q1. The authors used the term "xylyl" in the paper. However, xylyl, as substituent, is dimethylphenyl group. I am afraid that "xylyl'' has nothing to do with structures 3a-f. The "xylyl"term is incorrect in this paper. It is a laboratiry slang! Better to use another term for a discription of structures 3.
Response Q1: The term "xylyl-linked" often appears in journals. For example, Baker et al. J. Organomet. Chem. 2006, 691, 5845-5855; Dalton Trans. 2009, 7294-7307; Haqne et a. Inorg. Chem. Commun. 2012, 22, 113-119; Appl. Organometal. Chem. 2013, 27, 214-223; Demir et al. Appl. Organometal. Chem. 2009, 23, 520-523, and so on.
Q2. Page 2, lines 61-65: the description of spectral data is not necessarily! These data a given in Experimental Part and SI.
Response Q2: The necessity to include the discussion of the NMR spectra of compounds 3a-3f is to highlight the differences between the methylene groups of 3a-3f and those of 3e and 3f. In addition, the 1H NMR of the benzimidaolium proton and 13C NMR spectra of NCHN resonance serve as a support for the structure of our bis-benzimidazolium salts.
Q3. Page 4, entry 1 in Table 1: What is L? It is not clear.
Response Q3: The "L" in Table 1 means "bis-benzimidazolium salt L" in Figure 1.
Reviewer 3 Report
Dong-Sheng Lee et al. reported the development of effective Suzuki-Miyaura cross-coupling reaction of aryl chlorides using xylyl-bridged bis-benzimidazolium salts as ligands. The newly xylyl-bridged bis-benzimidazolium ligands shows improved catalytic activity compared to the previously reported alkyl-bridged ligand (L). However, high temperature experiments with L have not been reported in this paper, so the evaluation of catalytic activity is unclear. If the authors have carried out this experiment, the results should be reported.
The paper is very well written, and the compound data is sufficient. My evaluation is that the paper is publishable with minor scientific revisions.
- In Scheme 1, the authors use Mesyl for the mesityl group, which is generally a methanesulfonyl group. It should be written 2,4,6-Me3-C6H2, Mesityl, or Mes.
Comments for author File: Comments.docx
Author Response
Q1. However, high temperature experiments with L have not been reported in this paper, so the evaluation of catalytic activity is unclear. If the authors have carried out this experiment, the results should be reported.
Response Q1: High-temperature experiments with L were not examined in the t-BuOH. However, high-temperature experiments with L have been studied in the 1,4-dioxane at 110 oC. The results have been reported in Table 2. (see revised manuscript: Catalysts-1284776_1)
Q2. In Scheme 1, the authors use Mesyl for the mesityl group, which is generally a methanesulfonyl group. It should be written 2,4,6-Me3-C6H2, Mesityl, or Mes.
Response Q2: The mistake in Scheme 1 had been revised. (see revised manuscript: Catalysts-1284776_1)
Author Response File: Author Response.pdf
