Tributyl(1-((dimethylamino)(dimethyliminio)methyl)-1,4-dihydropyridin-4-yl)phosphonium Ditrifluoromethanesulfonate
Round 1
Reviewer 1 Report
The reviewed manuscript is about the synthesis and properties of Tributyl(1-((dimethylamino)(dimethyliminio)methyl)-1,4-dihydropyridin-4-yl)phosphonium di(trifluoromethanesulfonate). It is a very interesting paper extending the existing knowledge. After a minor revision, I can recommend the article for publication. My suggestions and questions are listed below:
- did you check other phosphines (for example triphenylphosphine)?
- the Authors should reorganize the references: they cited about 68 references which is definitely too much for such a short article; there are 68 references in the text but only 34 are listed in the section "References" - please check the references
- please check Figure 2 (too many TfO-)
- please add the title page to the SI
- figures A5 and A6: please check the captions - I suppose, Figure A5 is P{H}, and Figure A6 is without decoupling (by the way, what is the impurity about 86 ppm in Figure A5?).
Minor editing of English language required
Author Response
Dear editorial team, dear reviewer,
thank you for the timely review and the kind words. We have responded point by point below, with our responses marked in blue text. Please get back to us if you have any further remarks.
Sincerely,
Florian Mulks
- did you check other phosphines (for example triphenylphosphine)?
Thanks for the question. We added a paragraph to the manuscript detailing our efforts with other phosphines:
Analogous reactions with the poorer nucleophiles triphenylphosphine and triphenylphosphite did not lead to isolable adducts. No reaction was observed with triphenylphosphite. Triphenylphosphine led to the formation of sets of broad 1H NMR signals indicative of the desired 1,4-DHP but we were able to reisolate both starting materials through washing with Et2O, which dissolved the phosphine. This suggests that triphenylphosphine reversible adds to DIPy 1 which may be useful for promoting other functionalisation reactions.
- the Authors should reorganize the references: they cited about 68 references which is definitely too much for such a short article; there are 68 references in the text but only 34 are listed in the section "References" - please check the references
Our sincere apologies. Apparently we mistreated the EndNote library in some way leading to the removal of half of the references. The introduction ends with 33 references, which we believe should be rather adequate. We use a rather complex computational pipeline that needs lots of citations. Most of the employed methods were published in this century. Thus, we do not see much leeway in removing some of the citations by viewing them as common knowledge.
- please check Figure 2 (too many TfO-)
Apologies. We spotted this error just after the submission. Done.
- please add the title page to the SI
Done.
- figures A5 and A6: please check the captions - I suppose, Figure A5 is P{H}, and Figure A6 is without decoupling (by the way, what is the impurity about 86 ppm in Figure A5?).
Absolutely, thanks for spotting this. The trace impurity is likely, by analogy to the known [Et3POPEt3]OTf2 (87.2 ppm) the corresponding [Bu3POPBu3]OTf2.
To the main text was added:
Traces of 1 and [Bu3POPBu3]OTf2 were detected in 1H and 31P NMR spectra, respectively. The latter was identified by analogy of the 31P NMR shift (87 ppm) to the known shift of [Et3POPEt3]OTf2. (87 ppm).[30]
To the figure label A5 was added:
The trace impurity at 86.6 ppm is likely [Bu3POPBu3]OTf2.
We have additionally removed the unnecessary brackets from all mentions of ditrifluoromethanesulfonate (ex di(trifluoromethanesulfonate)) and a wrongly placed comma. We removed parts of the header and footer in the SI document, which we believe should not enter the final version.
