Electrochemical Thiocyanation/Cyclization Cascade to Access Thiocyanato-Containing Benzoxazines
Round 1
Reviewer 1 Report
The manuscript established an electrochemical approach for the thiocyanation of ortho-vinyl amides without a catalyst or oxidant. With optimization of reaction conditions, different substrates have been explored to demonstrate availability of the electrochemical strategy. After carefully evaluating the manuscript, I recommend its publication with a major revision. More detailed comments are as follows:
1. In 2.1. Condition optimizations, line 68, the description of the solvent system is confusing. “0.5 M CH3CN as the solvent”, means it’s a mixture solution including 0.5 M CH3CN? What was the solvent? “1 equivalent H2SO4 as the acid”, what was the standard for 1 equivalence.
2. In Table 1, the note letter “a” and “b” should be italic.
3. In Table 1, the sizes of “carbon rod and Pt plate” should be provided.
4. In line 75, page 3, the full name should be given in the first mention of “SS or Ni plate”.
5. In line 89, 2.2. Scope of substrates, the express of “N-dimethylamino 3h.” is incorrect, and the authors should give a correct name of 3h.
6. Chemical reactions, mechanisms and flow diagrams should be called schemes, while a picture or a diagram calls figure, therefor, the “Figure 1, 2, 3A, 4” should be given as “Scheme 1, 2, 3A, 4”.
7. In Figure 2, page 4, the compound 3n was not referred in the manuscript.
8. In Figure 3A, the text referred that when 2.0 equiv. radical scavenger TEMPO was added, only trace amount of 3a was observed. Whether the substrate 1a was recovered or other compounds had been discovered or detected?
9. In line 132-133 and 136, page 5-6, the structures of compounds “1-1, 1-2, 1a-1wa” should be given or cited.
10. The data of HRMS of 3e, 3g, 3q and 3r should be included in the manuscript. And in the SI, the formula of the four compounds did not match the calculated exact mass.
11. The compounds should be further purified to offer clean spectra, especially compounds 3a, 3d, 3i, 3l, 3o and 3n. The 13C NMR spectra of the most products appeared impurities at around 30.0 ppm.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Electrochemical organic synthesis has been regarded as a practical and green method in radical chemistry. Lei and co-workers have developed an electrochemical thiocyanation/cyclization cascade to construct benzoxazine under mild conditions with extra catalyst-free and oxidant-free conditions. It contributes a synthetic route towards thiocyanates with its good functional group tolerance and excellent performance under air. Therefore, this reviewer would like to recommend this manuscript be published on catalysts.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
In this manuscript, the authors explored an electrochemical oxidative cyclization of ortho-vinyl aniline to access various SCN-containing benzoxazines. The reaction has mild conditions, extra catalyst-free and oxidant-free system. The feature of good tolerance for air present the potential application of this method. I believe that this method could attract the interest of many readers, and it will promote the development of electrochemical synthesis. To sum up, it is an interesting work to construct thiocyanato-containing benzoxazines under electrochemical conditions. However, the manuscript needs some modifications as follows:
1. The content of the abstract should be further enriched.
2. In Figure 2, the groups of R2 only are methyl and phenyl. Whether other substituent species can participate in the reaction? if so, please list them. If not, please explain the reasons.
3. In the reaction conditions of Figure 2, you use 1 (0.3 mmol) (Page 4, Line 98) to participate in the reaction, while in the Characterization of product 3d (Page 6, Line 153) and detail descriptions for product 3d (Page S8 of Supporting Information) is 0.5 mmol. Why is the scale of reaction different before and after description? Please give your reasons.
4. In Figure 3A, both the structure of product 3a and radical adduct should be listed, which will make the control experiments more complete.
5. The related synthesis application of the electrochemical thiocyanation/cyclization cascade reaction or thiocyanato-containing benzoxazines could be further discussed and studied in the paper, which will promote the further development of application potential in this field.
6. “CDCl3” (Page 7, Line 204) and “CDCl3” (Page S9, last Paragraph) should be corrected as “CDCl3”, “By 1H NMR” (Page 9, Line 296) should be deleted to make consistent with other formats, “13C NMR” (Page S14, penultimate Paragraph) should be bold, please check format and correct all in the next revision.
7. It is recommended that the layout should be adjusted to make the page neat, for example, page 4 and page 10.
8. It will be better to use a smaller font below the chart to make the page more elegant.
9. In mechanistic study (Page S5, Line 4), the 3a' adduct was detected by LC-MS. However, in the picture below it, 3a' was detected by GC-MS, you'd better check it carefully.
10. In the part of detail descriptions for products (from Page S7 to S15), Some products have HRMS, while others do not, please check all.
11. Please note the format errors in the references of Supporting Information (Page S15), it should add volume number and page number.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I have reviewed the authors' response to my comments, and I think the revision improves the overall quality and clarity of this work. Therefore, publication of this work is recommended.