Molecule 25:

Correlation Table:

Molecule 25

A; 1.86 (s, 3H); these Hs are attached to a sp3 carbon that is attached to an sp2 carbon. The double bond in the sp2 carbon cause the bond to be slightly more polar, so the Hs are slightly more deshielded, which causes a downfield shift.

B; 2.10 (multiplet, 2H); these Hs are attached to an sp3 carbon that is in the vicinity of two O groups, which cause this peak to be slightly more downfield shifted than a regular sp3 CH2 peak. Also, these Hs have many bond neighbors because the neighboring Hs are diastereotopic, causing the peak to be a multiplet.

C; 2.70 (multiplet, 2H); these Hs are attached to an sp3 carbon that is attached to an C=O, causing the peak to be more downfield-shifted than a normal CH2 peak. It is a multiplet because its neighboring Hs are diastereotopic.

D; 4.78 (t, 1H); this H is strongly downfield-shifted because the C that it is attached to is also attached to a protected O group, which causes it to be strongly deshielded. Also, it is a triplet because its neighboring two Hs are diastereotopic.

E; 5.72 (s, 1H); this H is more deshielded because it is on an sp2 carbon, which is in the vicinity of a C=O, causing the peak to be more downfield-shifted.

F; 5.92 (s, 1H); this H is more deshielded and more downfield because it is closer to the C=O than its diastereotopic partner E because of the stereochemistry of the double bond.

G; 6.17 (d, 1H); this H is strongly shifted downfield because it is in an aromatic furan ring (which includes an O in the ring), causing it to be very deshielded. It is a doublet because it has an aromatic H bond neighbor.

H; 6.30 (dd, 1H); this H is very downfield-shifted because it is in an aromatic furan ring which causes it to be strongly deshielded. It is a doublet of doublets because of its neighboring aromatic Hs.

I; 7.33 (d, 1H); this H is extremely deshielded and shifted very far downfield because it is next to the O in the aromatic furan ring, which causes extra deshielding.