In this paper, two new norbornadienes with bromine substituents have been synthesized and characterized. The researchers have investigated photoisomerisation of two new norbornadienes to quadricyclanes. The synthetic plan is comprehensibly outlined and the results are well documented. However, as the article stands, the NMR data needs correction. These points are enumerated below.
1. In the 1H-NMR data of compound 4, “q” term must be two “doublet”. As methylenic carbon is adjacent to chiral carbon, it is clear that diastereomeric methylene hydrogen atom resonate at different regions as expected and must be two doublet (typically AB system). So, two different shift data and “d“ term must be used instead of “q” term.
2. Please check also 1H-NMR data of compound 6. The signal at 2.16 ppm is requiring to revision. The diastereomeric methylene hydrogen cannot be given as only one “doublet”. 13-NMR data of compound 6 is also need correction. The signal at 77.58, 77.26, and 76.94 ppm cannot be belong to structure and it must be signal of solvent (CDCl3).
3. Please check also 13C-NMR data of compound 8. I think that signal of carbonyl group is missing. Please check also a missing data at olefinic region and excess signal at (6.42 ppm ?) aliphatic region.