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   CP3 calculation: step 2

Check assignments

The applet displays the assignments that it is currently using. It orders the atoms in order of decreasing chemical shift. The order can be altered by typing new assignments into the text field. For example, the initial assignment might be given as:
202.200   C1
 45.700   C2
 15.500   C3
 13.600   C4
C3 and C4 are rather close to each other. There may be some reason, such as 2D NMR data, to swap them around. The text field should be edited to give:
202.200   C1
 45.700   C2
 15.500   C4
 13.600   C3
Alternatively, it may be that C3 and C4 are thought to be so close that it is not possible to assign them with any certainty. This can be entered as:
202.200   C1
 45.700   C2
 15.500   C3,C4
 13.600   C3,C4
The program will keep the assignments of C1 and C2 which have been entered, but will swap C3 and C4 as necessary to give the best match.

Now that you have the right assignments:


Assigning the Stereochemistry of Pairs of Diastereoisomers Using GIAO NMR Shift Calculation
S. G. Smith and J. M. Goodman J. Org. Chem. 2009, asap
DOI: 10.1021/jo900408d



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department of chemistry University of Cambridge