The "Summary of Invention" explains that "[t]he process of the invention shown in Scheme A provides an improved synthesis of taxol and related structures ...".
Taxol process and compounds Yun Gao et al: "
On paper, this looks like a very clever idea. After esterification, the amino protecting group is removed and the benzoyl group walks from the oxygen (leaving an alcohol), to the amine forming the required amide.
But there appears to be a problem.
A later patent, US7,169,774 from June 2007, discussing Cephalotaxanes reports,
Cephalotaxane derivatives and their processes of preparation and purification Jean-Pierre Robin et al: "
Quoting from the above image, "... although the attempts to acylate baccatin protected with a chain bearing an (hydroxyl group protected with a benzoyl group all failed)."
Which is a direct contradiction of the earlier patent.
This raises a couple of questions particularly with regard to the first patent.
A search of the United States Patent Office, specifically the 'public PAIR' site reveals that ...
"07-02-2002 Expire Patent
06-05-1998 Recordation of Patent Grant Mailed
Patent Expired Due to NonPayment of Maintenance Fees Under 37 CFR 1.362"
This post raises a lot of issues, perhaps I'll bring some of them up later.
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