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Sauron
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QSAR/QSPR is not so much a matter of theory as it is the assembly of empirical datasets and then the application of advanced statistical methodology
and a lot of silicon (but definitely still desktop) to fill in some gaps.
I recommend CODESSA from Semichem (Andy Holder at UM) with a AMPAC 8 front end although you can also go with a Gaussian 98W front end or MOPAC if you
prefer. Just don't mix results over different semiempirical (or ab initio) front end or you will be in GIGO hell.
Once you have an appropriate set of data to use to train your system you can accurately predict physical, chemical and biochemical properties for
compounds that have not been made yet. The accuracy is quite similar to the error found in empirical data sets. For boiling points for example the
sotware will give you a value +/- 8 C and the uncertainty in literature values is 7 C. This all works very well for bp's and related constants, GC
retention factors, density, refractive index, octanol/water partitions, not so well for melting points yet.
The true cross is the so called inverse problem. Give the system the physical and chemical and/or biochem/pharm properties desired and let the system
tell you all the molecular structures that will meet your wish list.
The inverse problem in QSPR remains unsolved.
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stimo-roll
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Maybe Wolff-Kishner Reduction with hydrazine hydrate and base will work? (JACS 68,2487,1946) or cycle can open?
[Edited on 2-5-2007 by stimo-roll]
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dedalus
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| Quote: | Originally posted by Sauron
I
Someone posted in an old thread that Zn/HCl would do this jon. Others (particularly @Nicodem) were skeptical.
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Don't you need the Zn to be amalgamated? I dimly recall this being called Clemmenson reduction.
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Nicodem
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It does not matter whether you amalgamate zinc or not since in neither case can you reduce amides or lactams (like I already said once in the other
thread from where Sauron quoted that).
| Quote: | Originally posted by stimo-roll
Maybe Wolff-Kishner Reduction with hydrazine hydrate and base will work? (JACS 68,2487,1946) or cycle can open? |
The Wolff-Kishner reduction only works on certain ketones and aldehydes so how could it be relevant for the reduction of delta-valerolactam? The
reference you cited certainly contains no amides as substrates.
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dedalus
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To think I once fancied myself an organic chemist.
That was back some time around the Norman Conquest, I also dimly recall.
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