9a-Phenyl-2,3,3a,3b,9a,9b-hexahydro-4H-furo[3‘,2’:3,4]cyclobuta- [1,2-b]chromen-4-one: A Flavone-Based [2 + 2]-Photocycloadduct

Round 1

Reviewer 1 Report

The manuscript “9a-phenyl-2,3,3a,3b,9a,9b-hexahydro-4H-furo[3',2':3,4]cyclobuta-2[1,2-b]chromen-4-one: a flavone-based 2+2-photocycloadduct”, authored by Lefarth and co-workers, describes the synthesis and the full characterization of a new photoadduct from the reaction between flavone and dihydrofuran. This is a nice piece of work, and deserves publication in Molbank, after minor revision, as described below:

- In Scheme 4, page 4: A reaction mechanism involves curved arrows to show the flow of electrons. Please, use curved arrows to show the formation of the new bonds.

Minor points:

- line 27: advances

- lines 55-56: Please, change for: Their medicinal properties include antioxidant, anti-inflammatory, anti-mutagenic, and anti-carcinogenic ones.

After addressing these points, the manuscript will be suitable to publication in Molbank.

Author Response

We would like to thank the reviewer for the constructive comments and the positive general remarks.

We made the following changes / corrections:

a) In Scheme 4, page 4: We have now exchanged the arrows and use curved arrows to show the formation of new bonds.

b) line 27: advances; lines 55-56: Please, change for: Their medicinal properties include antioxidant, anti-inflammatory, anti-mutagenic, and anti-carcinogenic ones.

These suggested corrections and changes were made in the revised version of the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the presented Short Note, Griesbeck and coworkers reported a peculiar example of [2+2] photocycloaddition which leads to the unexpected cis-syn-cis products in contrast to the general behavior that is witnessed in the literature cis-anti-cis. Besides the strategy and invoked concepts are not cutting-edge, the selection of the substrates and considerations regarding triplet-energy sensitization vs SET process are punctual and enrich the current knowledge of this type of chemistry. The overall manuscript writing is good, and considering the related background of the field, I consider it might be suitable for publication as currently presented.

Additional comments:

Have the authors tested substituted dihydrofurans (5)? What would they expect in terms of regioselectivity and reactivity? 

Please, a recent review about 2+2 should be cited: Eur. J. Org. Chem. 2021, 3303

Author Response

We thank the authors for their questions and suggestions and for the positive comments on our manuscipt.

Concerning the use of substituted dihydrofurans. This is of course a useful suggestion and we have not yet used other DHF, only ring-expanded dihydropyrans. Because Molbank is a journal where single compounds are reported and discussed, we have not added further information on alternatve cycloadditions (only in the discussion part).

We have now added a citation of the recommended 2021 review in Eur. J. Org. Chem. as reference 40. We have therefore shifted reference 40 (the X-ray data) to reference number 41.

Author Response File: Author Response.pdf