State what is meant by the term "semi-synthetic".b.

By 1988, and particularly with Potier's publication, it was clear to Holton as well that a practical semi-synthetic production route would be important. By late 1989, Holton's group had developed a semi-synthetic route to paclitaxel with twice the yield of the Potier process. , where Holton worked, signed a deal with to license this and future patents. In 1992, Holton patented an improved process with an 80% yield. BMS took the process in-house and started to manufacture paclitaxel in Ireland from 10-deacetylbaccatin isolated from the needles of the European yew. In early 1993, BMS were able to announce that they would cease reliance on Pacific yew bark by the end of 1995, effectively terminating the ecological controversy over its use. This announcement also made good their commitment to develop an alternative supply route, made to the NCI in their CRADA application of 1989.

Strategies for the Synthesis of Taxol ..

Discuss the advantages and disadvantages of extraction and semi-synthetic production of Taxol.c.

-xylosidase for semi-synthesis of Taxol


Total synthesis from crude-oil has been possible recently, but it is not a very green path in the production of Taxol.
Necessary Vocabulary
Chiral Centers:
atom bonded to 4 different elements/compounds (typically a carbon atom,
sp3
Enantioners: "
chiral molecules that are
mirror images
of one another...[and] are
non-superimposable
on one another.

Semi-synthetic route for the preparation of ..


(1960)
Scientists extracted an organic layer from the stem and bark of the Pacific yew tree,
Taxus brevifolia (where taxol gets its name, and is native to North America),
that

proved harmful to Walker-256 solid tumours
(1964)
Using chemical degradation and X-ray crystallography, Mansukh Wani determined the structure of paclitaxel
An Examination of a Anti-Cancer Drug
IB HL Chemistry Option D-7
Synthetic Extraction

(p.

Since 1994 the total synthesis of Taxol has been reported by several research groups in different countries.

A New Semisynthesis of Paclitaxel from Baccatin III

For a synthesis of enantiomerically pure C8-Desmethyl C, D-ring portion of Taxol via asymmetric Diels-Alder reaction of 2-siloxyfuran, with reaction scheme, click

A PRACTICAL AND EFFICIENT SYNTHESIS OF TAXOL …

Plant Cell Fermentation
Taxol was originally isolated from the pacific yew tree, but the extraction process is costly and environmentalists object to destroying the slow-growing trees to obtain the drug. Total synthesis is out of the question except as an academic exercise.

Trans-2-phenylcyclohexanol is used as a chiral auxiliary in the synthesis of anticancer drugs such as Taxol.

Patent US5254703 - Semi-synthesis of taxane …

Disadvantages of extracting Taxol: Jeopardizes the Pacific yew tree population, expensive to extract, takes a long time for plants to grow to the necessary size/age
Advantages of semi-synthetic production of Taxol: Higher yield of Taxol over-all, sustainable.
Disadvantages of semi-synthetic production of Taxol: Uses toxic chemicals and materials, thus producing toxic waste.

the completion of the total synthesis – with many semi-syntheses and ..

directed to a semi-synthesis for the preparation of ..

The initial part of the group's strategy was to convert the sugar ring to the carbocyclic C ring of the taxol structure. In 1991, the researchers subjected the glucose derivative to annulation to produce a tricyclic enone. This was the first reported application of this annulation reaction to the synthesis of annulatedsugars.

Synthesis of cis-Alkenes v Semi-hydrogenation of alkynes to ..

At a meeting in Dublin the group announced that they had recently taken the glucose-to-taxol synthesis an important stage further by constructing a taxoid C ring attached to a diene. "We now plan to construct dienophiles and then use the intramolecular Diels-Alder reaction to produce the A and B rings of thetaxoid structure."