(3a,8b)-5-Acetyl-3a-fluoro-6,8-dihydroxy-7,8b-dimethyl-3,3a-dihydrofuro[3,2-b]benzofuran-2(8bH)-one

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper by Filimonov and colleagues is a short note focused on the synthesis of a fluorinated usnetic acid derivative. The paper is interesting, well writtend and well presented, but the manuscript should undergo revision before further consideration.

 

Main comments:

• The introduction is very brief. The authors should describe in a short paragraph the relevance and properties of usnic and usnetic acid (10.1016/s0031-9422(02)00383-7; 10.1080/13543776.2018.1472239).
• Selectfluor: what is the structure and mechanism of this agent? If a proposed mechanism is described in Scheme 3, the authors could discuss this.
• The authors state that “We suppose, that the fluorine atom and the methyl group are on the same side of the furanone cycle of derivative 3 […] Thus, the compound 3 obtained by us is a mixture of enantiomers”. How did they come to this conclusion? I suggest further stressing the relevance of HMBC study. They should find relevance support in the literature for molecules in which this reaction was previously described.
• Cristallography should be indicated as a future perspective to address the concerns about chirality/isomers
• A brief conclusive paragraph indicating the potential uses of this molecule should be introduced.

 

The supplementary file also need revision:

• Please increase the size (or at least resolution) of NMR spectra, the numbers are barely readable
• Figure S15: Please comment on the base peak for the analysis of compound 3 (m/z = 217)
• HPLC chromatograms should be provided

Author Response

Dear Reviewer, 

Thank you for paying attention to our article and sharing your helpful comments.
The answer to your comments can be found in the attached file.

Best regards,
Dr. Aleksandr Filimonov
Department of Medicinal Chemistry
N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors addressed most of the comments. Still, I believe that chromatographic characterization should be carried out to provide an estimation of purity profile.