Past exam of the chemistry course of the year 3 of the natural sciences course of the University of Cambridge / 2022 / Paper 3 / 39 / a / Solution

The two substituents are $-\mathrm{C}{\mathrm{H}}_2-\mathrm{O}-\mathrm{C}(\mathrm{O})-\mathrm{CH}=\mathrm{CH}-\mathrm{Ph}$, with the alkene E, and $-\mathrm{C}(\mathrm{OH})(\mathrm{C}{\mathrm{H}}_3{)}_2$. The free bond at the left of each drawing attaches to the cyclohexene.

The A-D COSY correlation and $16.2\mathrm{Hz}$ coupling identify the trans cinnamate double bond. Five aromatic protons and four phenyl-carbon environments identify its monosubstituted phenyl ring. F is a two-proton OCH${}_2$ signal; its HMBC correlation to carbonyl 1 joins that methylene through oxygen to the ester. The two three-proton singlets N/O, their correlations to oxygenated quaternary carbon 10, and the missing OH resonance give the tertiary-alcohol substituent.