Starting from (−)-quinic acid, the title compound was synthesized in seven chemical steps and an overall yield of 35−38%.
The route of the improved Gilead synthesis was not changed.
However, significant improvements in each step led to a doubled
overall yield, a 30% reduction in the number of unit operations,
and an excellent quality (≥99%) of the resulting epoxide. A
highly regioselective method for the dehydration of a quinic
acid to a shikimic acid derivative and for the reduction of a
cyclic ketal was found. Alternatively, the title compound was
synthesized in six chemical steps and 63−65% yield from
commercially available (−)-shikimic acid. Compared to the
optimized quinic acid route, the production time was reduced
by about 50%. The quality of epoxide produced from either
natural product was equivalent. Therefore (−)-shikimic acid
is the preferred raw material. The absolute configuration of
the epoxide was determined by X-ray single crystal structure
analysis and it was demonstrated that the epoxide was stereoisomerically pure.
The clinical development of the first orally available neuraminidase inhibitor prodrug oseltamivir phosphate (Tamiflu™) proceeded very fast. In order to support this program an unprecedented team effort in chemical process research, development, piloting, production
and analytics took place, which allowed the successful launch of Tamiflu™ in 1999, only two and a half years after it was licensed from Gilead Sciences. This article describes selected aspects of the commercially used synthesis route and a brief summary of alternative syntheses
devised by Roche chemists.
Novel hexahydrospiro[piperidine-4,1'-pyrrolo[3,4-c]pyrroles that act as potent and selective orphanin FQ/nociceptin (N/OFQ) receptor (NOP) agonists were identified. The best compound, (+)-5a, potently inhibited 3H-N/OFQ binding to the NOP receptor (K(i) = 0.49 nM) but was >1000-fold less potent in binding to MOP, KOP, and DOP opiate receptors. Further, (+)-5a potently stimulated GTP gamma S binding to NOP membranes (EC50 = 65 nM) and inhibited forskolin-mediated cAMP accumulation in NOP-expressing cells (EC50 = 9.1 nM) with a potency comparable to that of the natural peptide agonist N/OFQ. These results indicate that (+)-5a is a highly selective and potent small-molecule full agonist of the NOP receptor.
A New Bromination Method for Phenols and Anisoles: NBS/HBF4·Et2O in CH3CN. -4-Nitrophenol (IIIc) and 2-nitroanisole require NBS/FSO3H for complete bromination. -(OBERHAUSER, T.; J.
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