Appeal No. 1997-1955
Application No. 08/423,498
optional choices of the triaryl antifertility compounds. In absence of
unexpected result it is prima facie obvious to choose some among many.
“When chemical compounds have ‘very close’ structural similarities and similar
utilities, without more a prima facie case may be made.” In re Grabiak, 769 F.2d 729,
731, 226 USPQ 870, 871 (Fed. Cir. 1985); see, e.g., In re Wilder, 563 F.2d 457, 195
USPQ 426 (CCPA 1977) (adjacent structural homologs and structural isomers). Be that
as it may, “generalization should be avoided insofar as specific chemical structures are
alleged to be prima facie obvious one from the other . . . there must be adequate support
in the prior art for the [ ] change in structure, in order to complete the PTO’s prima facie
case and shift the burden of going forward to the applicant.” 769 F.2d at 731-32, 226
USPQ at 872.
If we understand the examiner’s rationale correctly, it is that it would have been
obvious to treat endometriosis by administering either the subject benzothiophenes or the
corresponding benzofurans to a patient because of the structural similarity between the
compounds, as well as Crenshaw II’s classification of certain benzothiophenes and
2
benzofurans as “potential antifertility agents.” Nevertheless, in our view, the evidence
relied on by the examiner does not support her conclusion that the benzothiophenes of the
2The examiner has not explained the relevance of the Erber and Crenshaw I
references in the rejection of the claims, and indeed, we are unable to discern any. We
note that the examiner, unfortunately, relies on an abstract of Erber, rather than the
complete document; the very limited information available in the abstract appears to have
little or no bearing on the issue at hand. Crenshaw I describes 2-phenyl-3-tertiary-
aminoalkoxy phenyl and corresponding tertiaryaminoalkyl thio benzofurans, but does not
involve substitution of oxygen for sulfur in the base ring structure.
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