Re: Poster 30 (Raymond Jones)

Raymond Jones (
Mon, 26 Jun 1995 18:25:59 +0000

>Poster 30 Raymond Jones
>( ):
>We understand that you observed epimerization of your 1,3-dipolar
>cycloadducts during purification but could not corroborate your
>experimental findings with modeling studies.
>Applying higher levels of theory in your calculations may change
>this observation though we understand that such calculations may
>be prohibitive due to high CPU requirements.
>But have you considered performing the calculations using a Lewis-acid
>complex with your cycloadducts? BF3 could provide you an inexpensive
>mode; and this model may, perhaps, represent your experimental conditions
>for purifications and characterizations better.
>see Guner et al. J. Org. Chem., 1990, Vol. 55, page 28, for a similar

Dear Dr Guner - thank you for your suggestion. Our knowledge of
calculations is very primitive, so I need all the help I can get. Is it
simpler to use just a proton rather than BF3 ? Or will size be significant,
do you think, given that this may happen on silica gel ? If we use a
charged moiety, which software or forcefield will be advisable as best able
to handle it ?

Dr Raymond C F Jones
Department of Chemistry
University of Nottingham
University Park
Nottingham NG7 2RD, UK
Phone: +44 (0)115 951 3526; Fax: +44 (0)115 951 3564

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