September 2, 2011
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs
Diastereotopic protons that are also anisochronous exhibit different chemical shifts. The purpose of this puzzle is to understand a general trend for CH2 groups.
If the following structure, shown below, were dissolved in CDCl3 and a 1H NMR spectrum were acquired on a 500 MHz instrument, which of the following three CH2’s would most likely be anisochronous?
IUPAC: methyl 7-hydroxy-3,5-dioxo-7-phenylheptanoate
InChi Key: FOGURBALCWIVHU-UHFFFAOYSA-N
I guess A, since it is the closest to the chiral center.