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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