[tecky]

Dear all,

May I know what types of two dimensional nmr should performed to acertain the stereochemistry of my newly synthesized compound.

Is it noesy-H, Noesy-C, Coesy-H and coesy-C, homonuclear, heteronuclear, dept or etc. or combination.

Thank you !
Best Regards

[tmartin]

A question that comes to mind for me is what type of molecule are you trying to analyze?  I would probably go about analyzing a straight chain compound differently than a cyclic molecule.  When I've done 2-D proton NMR it has been both COSY and NOESY, in order to use both sets of info together. A COSY will tell you which protons are adjacent to one another while a NOESY will tell you through space interactions (what that proton is close to in the molecule).

Another question I have is how many stereocenters are you trying to determine?  And is this a carbinol stereocenter?  If you are trying to determine one stereocenter that is an alcohol perhaps you would consider using the Mosher Ester analysis.

[tecky]

Dear Tmartin,

1) My compound is basically alkaloids (conjugated aromatic cylic group).There is 3-6 carbinol
    stereocentre. I need to know the space configuration and orientation also.

Thank you !
Best Regards

A question that comes to mind for me is what type of molecule are you trying to analyze?  I would probably go about analyzing a straight chain compound differently than a cyclic molecule.  When I've done 2-D proton NMR it has been both COSY and NOESY, in order to use both sets of info together. A COSY will tell you which protons are adjacent to one another while a NOESY will tell you through space interactions (what that proton is close to in the molecule).

Another question I have is how many stereocenters are you trying to determine?  And is this a carbinol stereocenter?  If you are trying to determine one stereocenter that is an alcohol perhaps you would consider using the Mosher Ester analysis.

[tmartin]

tecky,

With a molecule as you're describing I would probably try to use both proton COSY and NOESY.  You may need the COSY to help unambiguously assign which proton corresponds to which signal and all around connectivity.  Once you know that (unless you have a neat spectrum and already do), you could look at the NOESY data to determine which protons "see" one another to determine relative stereochemistry.  Also, if you have an idea of the stereochemistry you should have, that could help too.  If the compound has been synthesized before you can probably find spectra in the literature to compare to, if not, you can have some fun with proton 2D 
Hope this helps.