The first 6 peaks were determined to be the hydrogens on the aromatic rings on either side of the molecule. The hydrogens on the ring adjacent to the double bond should generally have higher shifts than those on the other ring, but shifts between “matching” hydrogens should be close. Using this information, the 6 peaks were assigned in pairs of two to the pairs of “matching” hydrogens on the rings, the higher of the two shifts always going to the hydrogen in the pair on the ring adjacent to the alkene.

The 1H peaks at 6.45, 6.12, 5.99, and 3.74 ppm were assigned to be the four alkenic hydrogens. The peak at 6.45 ppm was assigned to the alkenic hydrogen nearest to the carbonyl, and the peak at 6.12 ppm was assigned to the other hydrogen on that alkene. These two assignments were made using coupling constant and expected shift values.
The other two alkenic peaks were difficult to assign. Based on expected shielding effects, the peak at 5.99 ppm should be assigned to the hydrogen adjacent to the aromatic ring, but the coupling constant of 8.0 Hz for the other peak matches the coupling constant from a previous aromatic hydrogen assignment. Based on multiplicity, however, the peak at 5.99 ppm was assigned to the hydrogen on the remaining alkene closer to the aromatic ring, and the peak at 3.74 was assigned to the hydrogen on the alkene farther from the aromatic ring. These were the most uncertain assignments of the molecule.

The 5H multiplet at 5.94-5.85 ppm was assigned to the 4 hydrogens in group j to maintain consistency with the assignment given to the similar hydrogens in molecule 20.

The multiplet at 3.66-3.57 ppm was assigned to the two hydrogens on the 4-membered rings adjacent to alkenes. The integration for this peak is 1H, but previously, a 5H peak had been assigned to 4H, so the number of hydrogens still works out with this assignment. Additionally, for the following assignments to make the most intuitive sense, this peak must be assigned to these two hydrogens.

The 4H multiplet at 3.52-3.38 ppm was assigned to the hydrogens closest to the nitrogen on the 6-membered ring adjacent to the alkene.

The following 4H multiplet at 3.27-3.06 ppm was assigned to the “matching” hydrogens closest to the nitrogen on the other 6-membered ring in the molecule. The former hydrogens are more deshielded than the latter because they are adjacent to an electron-withdrawing alkene.

The 2H multiplet at 3.05-2.93 ppm was assigned to the remaining two hydrogens on the central 4-membered ring. Relative shift assignments for the 4 hydrogens on this central ring correlate to the assignments made in molecule 20.

The 8H multiplet at 1.57-1.37 ppm was assigned to the matching 8 hydrogens in the nitrogen-containing 6-membered rings that are one bond farther from the nitrogen than the two previous assignments in this ring. They are less deshielded because they are farther from the electronegative atom, and therefore absorb as one multiplet instead of two distinct multiplets.

Finally, the 4H multiplet at 1.35-1.19 ppm was assigned to the remaining 4 hydrogens on the 6-membered rings that are farthest from the nitrogen.