The molecule in question has the following structure:
The 13C NMR is given below:
My assignments are:
23.700 ppm, -CH3
65.569 ppm, CH adjacent to the -OH
66.138/66.183 ppm; 67.924/67.977 ppm, substituted Cp carbons with protons attached
68.344 ppm; Cp carbons
94.857 ppm; Quaternary C
Are these assignments correct? The Cp carbons usually appear between 80-95 ppm but they are shifted down for some reason (I'm not sure why).
Additionally, why are the substituted Cp carbons (non-quaternary) doublets? I thought it may be due to the presence of staggered/eclipsed forms of the molecule but this would affect all the carbon environments.