Appeal No. 2001-2138
Application No. 08/403,276
establish a prima facie case of obviousness of the other enantiomer. Where, as here,
there is evidence of unpredictability (e.g., Crossley), and no evidence of common
6
pharmaceutical or biological properties , the “presumed expectation” of similar properties
due to the similar structures is not well-founded.
Examination of the remaining cases cited by the examiner shows that words that
might be interpreted as establishing a prima facie case of obviousness of a claimed
stereoisomer over the enantiomer disclosed in the prior art are either dicta because they
were not necessary for the disposition of the case, or they were made within the context of
the record before the court, and are thus of limited general applicability.
In In re Adamson, 275 F.2d 952, 125 USPQ 233 (CCPA 1960) the court upheld an
obviousness rejection of claims to “[a] laevo-isomer of a compound . . . substantially
separated from the dextro-isomer” over references disclosing the racemate, i.e., a mixture
of equal amounts of the enantiomers. More specifically, the references disclosed
synthetically produced compounds of the same formula claimed. A chemistry text taught
that synthetically produced substances containing asymmetric carbon atoms responsible
for optical activity are optically inactive due to the formation of equal amounts of the laevo-
and dextro-isomers. Adamson at 953, 125 USPQ at 234. Adamson argued that the
We stress the absence of evidence predicting pharmaceutical or biological properties of the6
compounds because it is only in interactions with other chiral molecules that the properties of one enantiomer
will differ from its mirror image: all properties of the enantiomers that involve interactions only with achiral
molecules will be identical, by symmetry.
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