NHC-Catalyzed Reaction of Aldehydes for C(sp2)–O Bond Formation
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe review by Miyabeand Yamaoka presents a brief discussion on the NHC-catalyzed C−O bond formation based on the activation of aldehyde C(sp2)−H bonds. This topic is timely, and the review nicely summarizes the literature, providing a good overview of interest for specialists in the field and for newcomers alike, and certainly aligns with the scope of Catalysts. I recommend publication once the following points have been addressed.
1) Identifying these reactions as “Cross-Couplings” is misleading and not suitable here. The authors must remove it for clarity.
2) There are a few key reviews that are missing, which can be cited in the appropriate places. Asian J. Org. Chem., 2021, 10, 1861; Chem. Eur. J. 2022, e202202467; Org. Chem. Front., 2021,8, 6138; Chin. J. Chem., 2020, 38, 1167; Acc. Chem. Res. 2019, 52, 425; ACS Catal. 2017, 7, 4, 2583; Acc. Chem. Res. 2014, 47, 2, 696; Org. Chem. Front., 2021, 8, 6138-6166; Catalysts 2018, 8, 549; ChemCatChem, 2012, 4, 937.
3) There are a few key publications that are missing in the discussion. For example: Angew Chem Int Ed 2010, 49, 9266; Org Lett 2013, 15, 50; Org. Lett. 2011, 13, 4080; Org Biomol Chem 2012,10, 848; Chem Commun 2012, 48, 5361; Eur J Org Chem 2011, 2011, 6527; Org Lett 2010, 12, 4552; Angew Chem Int Ed 2008, 47, 8727; Chem Asian J 2012, 7, 872; Nat Commun 2017, 8, 10.1038/ncomms15598; ACS Catal 2019, 9, 10971; Chem Eur J 2020, 26, 818; Org Lett 2013, 15, 1756; Asian JOC 2019, 8, 1067; Chem Eur J 2019, 25, 7469; Org Chem Front 2014,1, 936; Org Lett 2014, 16, 3676; Angew Chem Int Ed 2013, 52, 8588.
4) These oxidative C-O bond-forming reactions have versatile applications. If the authors can discuss it in the end of the review, it will impact the review positively. For example: Green Chem 2017, 19, 2477; React Chem Eng 2018, 3, 816; Org Biomol Chem 2018, 16, 8955; Polym Chem 2022, 13, 1350.
5) In section 4 the nomenclature of “Redox esterification of aldehydes” is probably not appropriate. Most of the reactions in the review are redox reactions. I think a more pertinent term should be “external oxidant-free redox esterification” or something very similar.
There are couple of typos and minor issues:
6) Please specify Bu and Pr groups as n-/i-/t-/sec
7) Scheme 2: E/Z should be italicized.
8) Scheme 19: “μl” should be “μL”
9) Scheme 19: The counteranion is missing in compound 68.
10) Scheme 32: There should be -NH2 in compound 110.
11) Scheme 40: In compound 130 it should be C6H4 instead of C4H4.
12) The bond angles of compound 156 is not appropriate.
13) Scheme 51: In the last scheme CH2CN should be MeCN.
Author Response
Thank you for your kind review of our manuscript. According your comments and suggestions, we revised the manuscript.
The important changing parts in the revised manuscript are highlighting as a yellow background.
(1) Identifying these reactions as “Cross-Couplings” is misleading and not suitable here. The authors must remove it for clarity.
<Answer> “Cross-Coupling” was revised to “Reaction” in Title. And also, several words “cross-coupling” were revised to “reaction” in text. Please kindly see changing parts highlighted as a yellow background.
(2) There are a few key reviews that are missing, which can be cited in the appropriate places. Asian J. Org. Chem., 2021, 10, 1861; Chem. Eur. J. 2022, e202202467; Org. Chem. Front., 2021,8, 6138; Chin. J. Chem., 2020, 38, 1167; Acc. Chem. Res. 2019, 52, 425; ACS Catal. 2017, 7, 4, 2583; Acc. Chem. Res. 2014, 47, 2, 696; Org. Chem. Front., 2021, 8, 6138-6166; Catalysts 2018, 8, 549; ChemCatChem, 2012, 4, 937.
<Answer> Thank you for your suggestions. References cited in “1. Introduction” were updated. These articles were added as references 6, 10, 12, 14, 15, 17, 19, 20 and 22.
(3) There are a few key publications that are missing in the discussion. For example: Angew Chem Int Ed 2010, 49, 9266; Org Lett 2013, 15, 50; Org. Lett. 2011, 13, 4080; Org Biomol Chem 2012,10, 848; Chem Commun 2012, 48, 5361; Eur J Org Chem 2011, 2011, 6527; Org Lett 2010, 12, 4552; Angew Chem Int Ed 2008, 47, 8727; Chem Asian J 2012, 7, 872; Nat Commun 2017, 8, 10.1038/ncomms15598; ACS Catal 2019, 9, 10971; Chem Eur J 2020, 26, 818; Org Lett 2013, 15, 1756; Asian JOC 2019, 8, 1067; Chem Eur J 2019, 25, 7469; Org Chem Front 2014,1, 936; Org Lett 2014, 16, 3676; Angew Chem Int Ed 2013, 52, 8588.
<Answer> Thank you for your suggestions. These articles were added as references 37, 38, 53, 54, 55, 56, 77, 82, 87, 88, 89, 92, 106, 112, 113, 138 and 215. And also, the following sentence was added at page 2. “Additionally, the oxidative esterification of aldehydes was studied using boronic acids, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) or alkyl halides [53−56].”
(4) These oxidative C-O bond-forming reactions have versatile applications. If the authors can discuss it in the end of the review, it will impact the review positively. For example: Green Chem 2017, 19, 2477; React Chem Eng 2018, 3, 816; Org Biomol Chem 2018, 16, 8955; Polym Chem 2022, 13, 1350.
<Answer> Thank you for your suggestions. References cited in “9. Conclusion and outlook” were updated. These articles were added as references 264, 265, 266 and 267. And also, the following sentence was added at page 36. “Furthermore, the oxidative C−O bond-forming reactions have been used for the synthesis of biomass-derived compounds as a sustainable alternative to petroleum compounds [264−267].”
(5) In section 4 the nomenclature of “Redox esterification of aldehydes” is probably not appropriate. Most of the reactions in the review are redox reactions. I think a more pertinent term should be “external oxidant-free redox esterification” or something very similar.
<Answer> “Redox esterification of aldehydes” was revised to “External oxidant-free redox esterification” in title of section 4. And also, the similar nomenclatures were revised in text. Please kindly see changing parts highlighted as a yellow background.
(6) Please specify Bu and Pr groups as n-/i-/t-/sec
<Answer> “Bu” was revised to “n-Bu” in Scheme 2 and 19.
“Pr” was revised to “n-Pr” in Scheme 33.
(7) Scheme 2: E/Z should be italicized.
<Answer> E/Z was italicized.
(8) Scheme 19: “μl” should be “μL”
<Answer> “μl” was revised to “μL”.
(9) Scheme 19: The counteranion is missing in compound 68.
<Answer> The counteranion was added.
(10) Scheme 32: There should be -NH2 in compound 110.
<Answer> “-NH3” was revised to “-NH2”.
(11) Scheme 40: In compound 130 it should be C6H4 instead of C4H4.
<Answer> “C4H4” was revised to “C6H4”.
(12) The bond angles of compound 156 is not appropriate.
<Answer> The bond angles of compound 156 was revised.
(13) Scheme 51: In the last scheme CH2CN should be MeCN.
<Answer> “CH2CN” was revised to “MeCN”.
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this paper, the authors reports the NHC-catalyzed C-O formation reaction. Recent advances are summarized. The paper is well prepared. Thus, it may be published after revisions:
(1) References cited in introduction part are old and need to be updated. The authors should search recent articles and cite the related reviews, e.g. 10.1016/j.cclet.2023.108544
(2) Please be careful about the format. For example, “N-heterocyclic”, “N” should be in italic font. “β-pyridylation”, also, “β” should be in italic font.
(3) The dots of radical in Schemes are too large and should be revised.
(4) In Scheme 51, what does “Red” mean? Redox?
Comments on the Quality of English LanguageMinor revisions
Author Response
Thank you for your kind review of our manuscript. According your comments and suggestions, we revised the manuscript.
The important changing parts in the revised manuscript are highlighting as a yellow background.
(1) References cited in introduction part are old and need to be updated. The authors should search recent articles and cite the related reviews, e.g. 10.1016/j.cclet.2023.108544
<Answer> References cited in “1. Introduction” were updated. References 6, 10, 12, 14, 15, 17, 19, 20, 22 and 27 were added for introduction. Review (10.1016/j.cclet.2023.108544) was cited in reference 27.
(2) Please be careful about the format. For example, “N-heterocyclic”, “N” should be in italic font. “β-pyridylation”, also, “β” should be in italic font.
<Answer> In the case of N-(names of chemical), “N” was revised to italic font. I asked section managing editor about the font of Greek letters. Consequently, for the Greek letters in the main text, regardless of they are in italics or not, keep the author provided and make sure the whole article is identical. Therefore, we used the normal font (non-italic font) for Greek letters.
(3) The dots of radical in Schemes are too large and should be revised.
<Answer> The dots of radical were revised in Schemes 2, 10, 19, 46, 47, 49, 50 and 51. And also, the dots of NHC were revised in corresponding Schemes.
(4) In Scheme 51, what does “Red” mean? Redox?
<Answer> The reduction of phenoxy radical give anion; thus, the structure of anion was added in Scheme 51.
