Actually, when my supervisor (our prof) told me to give a presentation regarding
Noble winning chemical work i.e., palladium catalyzed cross-couping reactions
which are mainly the Heck, Negishi and Suzuki reactions, made me to search in
the google and i have found many articles, trying to gather them to present them
in a story mode which i mean to make them simpler and easily understandable.
At the end of the 1980s, Scuba divers in the Caribbean Sea collected the marine sponge Discodermia dissoluta. At a depth of 33 meters (108 feet) they found a little creature that lacks eyes, a mouth, stomach and bones. At first sight it appears primitive, but its inability to escape enemies has turned Discodermia dissoluta and other marine sponges into masters of chemistry. They have a remarkable ability to produce large and complex chemical molecules that are poisonous and that prevent other organisms from exploiting them.
Researchers have discovered that many of these poisons have therapeutic
properties; they can function as antibiotics or as anti-viral or
anti-inflammatory medicines. In the case of Discodermia dissoluta,
the first laboratory tests revealed that the substance discodermolide
could in the future be used as a chemotherapy drug. Among other things,
it stopped cancer cells from growing in test tubes.
Download Pdf
Noble winning chemical work i.e., palladium catalyzed cross-couping reactions
which are mainly the Heck, Negishi and Suzuki reactions, made me to search in
the google and i have found many articles, trying to gather them to present them
in a story mode which i mean to make them simpler and easily understandable.
At the end of the 1980s, Scuba divers in the Caribbean Sea collected the marine sponge Discodermia dissoluta. At a depth of 33 meters (108 feet) they found a little creature that lacks eyes, a mouth, stomach and bones. At first sight it appears primitive, but its inability to escape enemies has turned Discodermia dissoluta and other marine sponges into masters of chemistry. They have a remarkable ability to produce large and complex chemical molecules that are poisonous and that prevent other organisms from exploiting them.
 |
| Discodermia dissoluta sponge |
Researchers have discovered that many of these poisons have therapeutic
properties; they can function as antibiotics or as anti-viral or
anti-inflammatory medicines. In the case of Discodermia dissoluta,
the first laboratory tests revealed that the substance discodermolide
could in the future be used as a chemotherapy drug. Among other things,
it stopped cancer cells from growing in test tubes.Download Pdf
The Researchers tried to synthesize discodermolide and other naturally available drugs like
Palytoxin, that was first isolated from a coral in Hawaii in 1971. Palytoxin consists of 129
carbon atoms, 223 hydrogen atoms, three nitrogen atoms, and 54 oxygen atoms.and it is very
difficult to synthesize in a laboratory as one should link one carbon to another and it is not as easy
as said. First, scientists tried the Grignard reaction. The Grignard method of coupling carbon
atoms has been enormously important in chemistry. But when it comes to creating large and complex molecules, the method has its limitations. The carbon atom in the unstable Grignard reagent does not
behave predictably. When the reagent has several different carbon atoms to react with, too many
unwanted by-products are created.
The palladium-catalyzed cross-coupling reaction solves this problem and provides precision
in the process.When the carbon atoms meet on a palladium atom, chemists do not need to activate
the carbon atom to the same extent. This entails fewer by-products and a more efficient reaction.
Instead of the Grignard reagent Richard Heck began to use chemical compounds called olefins.
In an olefin the carbon atom is naturally slightly activated and when it binds to the palladium atom it
becomes even more likely to react with another carbon atom.
In 1977, Ei-ichi Negishi developed a variant of the Grignard reagent when he substituted magnesium for
zinc. The carbon becomes less reactive when using zinc, but the zinc atom transfers the carbon atom to the
palladium atom. When the carbon atom subsequently meets another carbon atom on the palladium atom,
they are then prone to couple.
Two years later, Akira Suzuki used the element boron. It is the mildest activator so far and is even less toxic than zinc, which is an advantage when it comes to large-scale applications. For instance, Suzuki’s reaction is used in the commercial synthesis (thousands of tons) of a substance that protects agricultural crops from fungi.
Today the Heck reaction, Negishi reaction and Suzuki reaction are of considerable importance to chemists.
Richard F. Heck
Born: 15 August 1931, Springfield, MA, USA
Affiliation at the time of the award: University of Delaware, USA
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"
Know about Richard Heck and his work
Born: 15 August 1931, Springfield, MA, USA
Affiliation at the time of the award: University of Delaware, USA
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"
Know about Richard Heck and his work
Ei-ichi Negishi
Born: 14 July 1935, Changchun, China
Affiliation at the time of the award: Purdue University, West Lafayette, IN, USA
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"
Know about Ei-ichi Negishi's and his work
Affiliation at the time of the award: Purdue University, West Lafayette, IN, USA
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"
Know about Ei-ichi Negishi's and his work
Akira Suzuki
Born: 12 September 1930, Mukawa, Japan
Affiliation at the time of the award: Hokkaido University, Sapporo, Japan
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"
Know about Akira Suzuki and his work
Born: 12 September 1930, Mukawa, Japan
Affiliation at the time of the award: Hokkaido University, Sapporo, Japan
Prize motivation: "for palladium-catalyzed cross couplings in organic synthesis"Know about Akira Suzuki and his work
One of the most spectacular examples where palladium-catalyzed cross coupling has been used is in the test
tube creation of palytoxin – a dinosaur in the chemical world and it is a naturally occuring poison.
In 1994, scientists managed to re-create this enormous molecule, partly with the help of the Suzuki reaction.
Links and further reading
Additional information on this year’s Prizes, including a scientific background article in English, may be
found at the website of the Royal Swedish Academy of Sciences, http://kva.se, and at http://nobelprize.org.
The latter also includes a web-TV version of the press conference at which the awards were announced.
Information on exhibitions and activities related to the Nobel Prizes and the Prize in Economic Sciences
may be found at www.nobelmuseet.se.
Scientific articles
Review articles
1) Negishi, E. (1999) A profile of Professor Richard F. Heck Discovery of the Heck reaction. Journal of
Organometallic Chemistry 576, p. XV-XVI.
2) Rouhi, M. (2004) Chem. & Eng. News, 82 (36), Sept. 6, p. 49–58. [Article about Suzuki.]
de Meijere, A. and Diederich, F. (Eds.) (2004) Metal-Catalyzed Cross-Coupling Reactions, vol. 1 and
2,Wiley-VCH, Weinheim. pp. 916.
3) Buchwald, S. L. (Ed.) (2008) Accounts of Chemical Research, Vol. 41, Nov. 11, p. 1439–1564.
[Special issue on Cross Coupling.]
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