(7aR*,7bR*)-7a,7b-Dihydro-15H-dibenzo[f,f′]cyclopenta[1,2-b:5,4-b′]dichromene

Round 1

Reviewer 1 Report

This paper reports an unexpected product and a possible mechanism involving a Diels-Alder reaction of a allene followed by an iso-Nazarov cyclization.  These are hardly expected, but they do provide a plausible explanation for the obtained product, which is well-characterised.   I recommend publication in Molbank after the authors have considered the following points: 

The introduction sets the scene well although there are maybe one or two unneeded self-citations [refs. 16-19].   

Scheme 1 has reproduced very poorly in the review PDF.    It should be rendered in colour (like scheme 2), as should scheme 3. 

(line 75)   ...the structure of 3 was confirmed by single-crystal X-ray diffraction.  Some more detail could be added here re the conformations of the three central rings and some key dihedral angles.   A few key bond lengths (C12-C13, C13-C14, C14-C15...) could be cited to support the assignments of formal single and double bonds in 3. 

Fig 2: labels very small 

(line 152)   State the R-factors (residuals).  

Author Response

Comment 1: The introduction sets the scene well although there are maybe one or two unneeded self-citations [refs. 16-19].

Responce 1: we retained only two references 15,16

Comment 2: Scheme 1 has reproduced very poorly in the review PDF.    It should be rendered in colour (like scheme 2), as should scheme 3. 

Responce 2: corrected

Comment 3: (line 75)   ...the structure of 3 was confirmed by single-crystal X-ray diffraction.  Some more detail could be added here re the conformations of the three central rings and some key dihedral angles.   A few key bond lengths (C12-C13, C13-C14, C14-C15...) could be cited to support the assignments of formal single and double bonds in 3. 

Responce 3: corrected

Comment 4: Fig 2: labels very small 

Responce 4: corrected

Comment 5: (line 152)   State the R-factors (residuals).  

Responce 5: corrected