eee CIBA—GEIGY

Ardsley, New York 10502
Telephone 914 478 3131

April 19, 1976

Professor Carl Djerassi
Department of Chemistry
Stanford University
Stanford, California 94305

Deac Professor Djerassi:

Thank you for permitting us to use the CONCEN program for the past year.
We have used this program only for the most demanding structure problems
and therefore have not been a heavy user of the system. However, when
utilized, we have found the CONGEN program to be a valuable and effective

aid for structure elucidation problems.

We have used CONGEN to provide assurance that once a structure has deen pro-
posed on the basis of chemical and spectroscopic analysis that other, plau-
sible structures have not been overlooked, thereby providing a greater con-
fidence limit to our structural proposals. We have also utilized the program
to determine possible structures when the analytical data does not provide

a unique structure, and in this manner acquire additional chemical structures

for consideration. Both approaches represent assets to structure determination

work.

Clearly, the scope of CONGEN would be extended by making it available to
other industrial chemists involved with determining structures of organic
compounds. As you know, the industrial setting demands accurate results by
the most rapid and economical means available. Exposing CONGEN to a wider
range of industrial chemists would provide your staff with more experience
with diverse structure problems and hence extend the versatility and utility

of the programs. However, in order to attain more participation, the computer

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Professor Djerassi -2- April 19, 1976

system would have to be made more readily accessible, especially during peak

We have been fortunate in this regard since the time zone difference

between Stanford and Ardsley enables us to use CONGEN early in the morning

hours.

when few others are using the SUMEX programs. However, when we attempt to use
the program later in the day, the system becomes fairly slow, to the point where

at times we find it more economical to simply log off and resume the following

morning.

We consider CONGEN as another complementary structure elucidation method at

CIBA-GEIGY and look forward to its continued use in the future.
Sincerely yours,
leper Karliner Ph.D,

Gy4up Leader
Analytical Research Department

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