argh. Broke chirality for ketones!
On Fri, Apr 21, 2017 at 11:27 AM, Robert Hanson <hans...@stolaf.edu> wrote:
>
>
> On Fri, Apr 21, 2017 at 11:10 AM, Bruce Tattershall <
> bruce.tattersh...@newcastle.ac.uk> wrote:
>
>> Dear Bob
>>
>>
>>
>> The chirality calculation is clearly useful.
>>
>>
>>
>> I have tried it on my chiral phosphorus compounds, e.g. as in
>>
>> https://www.staff.ncl.ac.uk/bruce.tattershall/structs/bpthiq.php
>>
>> and it finds the chiral carbons in the organic ligands and successfully
>> labels them (as R in this case),
>>
>> but it does not find the chirality of the phosphorus atoms to which they
>> are attached.
>>
>>
> It's a work in progress.
>
> Limitations:
>
> no parallel chirality paths
> not processing inositols correctly
> no lone-pair business
> standard E/Z, R/S, r/s only; no allenes, no planar asymmetry
>
>
>
>>
>> I have no idea of how this works, but would it be possible to extend it
>> easily to phosphorus chirality (for which
>>
>> one uses the same rules but counts the lone pair as lowest priority)?
>>
>>
> Lone pairs wouldn't be too difficult to add, particularly if they are
> limited to P and S. They are definitely in the IUPAC 2013 spec. I'd like to
> add imine stereochemistry as well.
>
>
>
>>
>>
>> When I first got into measuring NMR spectra of diastereomers of such
>> compounds about 15 years ago,
>>
>> I found it very hard to get my inorganic chemist’s head around the
>> chirality implications. It would
>>
>> have been very useful to have a tool to work it out for me.
>>
>>
>>
>> If you are going to elements other than carbon, then I guess that besides
>> phosphorus, the inorganic
>>
>> chemist’s favourite, the chirality at silicon, germanium and arsenic
>> could also be useful to people.
>>
>
> Silicon and ammonium are just like carbon, I think. As and P no problem.
>
> Definitely not going to higher valencies any time soon.
>
> Higher priorities are allenes and getting the darned inositol business
> working correctly. But maybe P and S and As are so easy I should just do
> them....
>
> Bob
>
--
Robert M. Hanson
Larson-Anderson Professor of Chemistry
St. Olaf College
Northfield, MN
http://www.stolaf.edu/people/hansonr
If nature does not answer first what we want,
it is better to take what answer we get.
-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900
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