Appeal No. 94-4265
Application 08/035,915
We agree with appellants that the Mead case does not support the examiner’s position. In
the Mead case, the court made a factual finding that
44. The only difference between the structure of isoxsuprine and that of
nylidrin is that isoxsuprine contains an oxygen atom adjacent to the right-hand phenyl
group or benzene ring whereas nylidrin has a methylene group (CH ) attached to the
2
benzene ring instead of the oxygen atom in the same position.
The court considered testimony and other evidence before it and concluded that
87. One of the many classical molecular modifications, in accordance with
the principles of bioisosterism, is the replacement a methylene group with an oxygen
atom in biologically active compound. Such substitution was well known prior to
1955 to produce compounds of similar biological activity to the lead compound, and
it would have been obvious for a medicinal chemist in that time period to have made
the substitution when seeking to modify a compound containing a methylene group,
provided, of course, that the substitution was chemically feasible in that particular
position.
88. In terms of the priority which a medicinal chemist would have
accorded to the isosteric replacement of oxygen for methylene in the nylidrin
compound prior to 1955, a medicinal chemist would have considered that
modification to be the second out of four which would logically have been attempted
in the search for an improved cardiovascular drug.
89. Another theory known in the organic chemistry art prior to 1955 which
posited that oxygen and methylene could be interchanged in compounds without
greatly affecting their physical properties was Grimm*s Hydride Displacement Law
....
90. Oxygen was said by Grimm to be interchangeable with the methylene
group. The modification of nylidrin which resulted from the interchanging of oxygen
and methylene was within the replacement rules taught by Grimm, although Grimm*s
law does not postulate any compounds which specifically related to isoxsuprine or
nylidrin.
91. A medicinal chemist seeking in 1955 to modify the compound nylidrin
in order to improve its biological properties would have been motivated to substitute
oxygen for methylene adjacent to phenyl in nylidrin because of the teachings of the
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