Appeal No. 2001-0665
Application 08/439,920
trimethylsilyl, triethylsilyl, and 1-methyl-1-methoxyethyl.1 The examiner argues that it would
have been prima facie obvious to use 1-methyl-1-methoxyethyl as a suitable hydroxy
protecting group at the 20 position on the C-13 sidechain of Holton’s compounds, this per
the teachings of Greene. According to the examiner, a person having ordinary skill in the
art would have recognized and understood that 1-methyl-1-methoxyethyl functions to
protect the hydroxyl group and is interchangeable with the specific protecting groups
disclosed by Holton. The examiner concludes that the combined disclosures of Holton and
Greene would have led a person having ordinary skill in the art to the claimed intermediate
having formula (VII), including the 1-methyl-1-methoxyethoxy group at the 20 position on the
C-13 sidechain.
Appellants contest the prima facie case of obviousness. They argue that Holton
discloses a “vast genus” of taxane intermediates containing a “hydroxy protecting group” at
the 20 position on the C-13 sidechain, but does not disclose their intermediate having
formula (VII) containing a 1-methyl-1-methoxyethoxy group at that position. Further,
appellants argue, the sidechain-bearing intermediates specifically disclosed by Holton are
structurally distinct from the intermediate of the appealed claims. According to appellants,
Greene does not cure the deficiencies of Holton because (1) Greene merely provides a
long list of groups which potentially may be employed in protecting a hydroxyl group; and
1 The Greene reference, relied on by the examiner, is a 1991 edition of the textbook referenced in
Holton.
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