Organic synthesis is the construction of organic molecules via chemical processes. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has developed into one of the most important aspects of organic chemistry. There are two main areas of research fields within the general area of organic synthesis- total synthesis and methodology. Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds that by definition contain carbon. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... Link titleAn organic compound is any member of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds that by definition contain carbon. ... A total synthesis is the complete chemical synthesis of complex organic molecules from simple, commercially available (petrochemical) precursors. ...

Total synthesis

A total synthesis^[1] is the complete chemical synthesis of complex organic molecules from simple, commercially available (petrochemical) or natural precursors. In a linear synthesis there is a series of steps which are performed one after another until the molecule is made- this is often adequate for a simple structure. The chemical compounds made in each step are usually referred to as synthetic intermediates. For more complex molecules, a convergent synthesis is often preferred. This is where several "pieces" (key intermediates) of the final product are synthesized separately, then coupled together, often near the end of the synthesis. A total synthesis is the complete chemical synthesis of complex organic molecules from simple, commercially available (petrochemical) precursors. ... In chemistry, the phrase chemical synthesis appears to have one of two meanings. ... Link titleAn organic compound is any member of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... A molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... A petrochemical is any chemical derived from fossil fuel. ... Natural is defined as of or relating to nature; this applies to both definitions of nature: essence (ones true nature) and the untouched world (force of nature). The natural sciences such as physics, chemistry etc. ... In chemistry a convergent synthesis is a strategy that aims to improve the effeciency of multi-step chemical synthesis. ...

The "father" of modern organic synthesis is regarded as Robert B. Woodward, who received the 1965 Nobel Prize for Chemistry for several brilliant examples of total synthesis such as his 1954 synthesis of strychnine^[2]. One of the most active research groups today is that of Kyriacos Costa Nicolaou of the Scripps Research Institute. Robert Burns Woodward: On the blackboard is the structure of chlorophyll, one of many complex molecules that he synthesized (National Academy of Sciences Press) Robert Burns Woodward (April 10, 1917-July 8, 1979) was an American organic chemist, widely regarded as the preeminent organic chemist of the century. ... List of Nobel Prize laureates in Chemistry from 1901 to the present day. ... Strychnine (pronounced (British) or (U.S.)) is a very toxic (LD50 = 1 mg/kg), colourless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as rodents. ... The Scripps Research Institute, in La Jolla, California is home to notable chemists such as K. Barry Sharpless and P. G. Schultz, as well as neurobiologist Gerald Edelman, and Nobel Laureate Kurt Wurtrich. ...

Methodology

Each step of a synthesis involves a chemical reaction, and reagents and conditions for each of these reactions need to be designed to give a good yield and a pure product, with as little work as possible^[3]. A method may already exist in the literature for making one of the early synthetic intermediates, and this method will usually be used rather than "trying to reinvent the wheel". However most intermediates are compounds that have never been made before, and these will normally be made using general methods developed by methodology researchers. To be useful, these methods need to give high yields and to be reliable for a broad range of substrates. Methodology research usually involves three main stages- discovery, optimisation, and studies of scope and limitations. The discovery may be due to serendipity, or may be from a flash of insight. Optimisation is where one or two starting compounds are tested in the reaction under a wide variety of conditions of temperature, solvent, reaction time, etc., until the optimum conditions for product yield and purity are found. Then the researcher tries to extend the method to a broad range of different starting materials, to find the scope and limitations. Some larger research groups may then perform a total synthesis (see above) to showcase the new methodology and demonstrate its value in a real application. A chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants. ... Yield may mean: In economics, yield is a measure of the amount of income an investment generates over time (related to return on investment). ... The word substrate can mean the following: In biochemistry, a substrate is a molecule which is acted upon by an enzyme. ... Serendipity is finding something unexpected and useful while searching for something else entirely. ...

Asymmetric synthesis

Many complex natural products occur as one pure enantiomer. Traditionally, however, a total synthesis could not easily make only a complex molecules as a racemic mixture, i.e., as an equal mixture of both possible enantiomer forms. The racemic mixture might then be separated via chiral resolution. In chemistry two stereoisomers are said to be enantiomers if they are mirror images of each other. ... In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecules. ... In chemistry two stereoisomers are said to be enantiomers if they are mirror images of each other. ...

In the latter half of the twentieth century, chemists began to develop methods of asymmetric catalysis and kinetic resolution whereby reactions could be directed to produce only one enantiomer rather than a racemic mixture. Early examples include Sharpless epoxidation (K. Barry Sharpless) and asymmetric hydrogenation (William S. Knowles and Ryoji Noyori), and these workers went on to share the Nobel Prize in Chemistry in 2001 for their discoveries. Such reactions gave chemists a much wider choice of enantiomerically pure molecules to start from, where previously only natural starting materials could be used. Using techniquess pioneered by Robert B. Woodward and new developments in synthetic methodology, chemists became more able to take simple molecules through to more complex molecules without unwanted racemisation, by understanding stereocontrol. This allowed the final target molecule to be synthesised as one pure enantiomer without any resolution being necessary. Such techniques are referred to as asymmetric synthesis. In chemistry and biology, catalysis is the acceleration of the reaction rate of a chemical reaction by means of a substance, called a catalyst, that is itself unchanged chemically by the overall reaction. ... Sharpless epoxidation is a chemical reaction of an allylic alcohol with t-butylperoxide and titanium tetraisopropylate to form an epoxide. ... Karl Barry Sharpless (born April 28, 1941) is a chemist renowned for his work on organometallic chemistry. ... Hydrogenation is a chemical reaction in which unsaturated bonds between carbon atoms are reduced by attachment of a hydrogen atom to each carbon. ... William S. Knowles (born June 1, 1917) is a American chemist. ... Ryoji Noyori (野依良治) (born September 3, 1938) won the Nobel Prize in Chemistry in 2001. ... List of Nobel Prize laureates in Chemistry from 1901 to the present day. ... Robert Burns Woodward: On the blackboard is the structure of chlorophyll, one of many complex molecules that he synthesized (National Academy of Sciences Press) Robert Burns Woodward (April 10, 1917-July 8, 1979) was an American organic chemist, widely regarded as the preeminent organic chemist of the century. ...

Synthesis design

Elias James Corey brought a more formal approach to synthesis design, based on retrosynthetic analysis, for which he won the Nobel Prize for Chemistry in 1990. In this approach, the research is planned backwards from the product, using standard rules^[4]. The steps are shown using retrosynthetic arrows (drawn as =>), which in effect means "is made from". Other workers in this area include one of the pioneers of computational chemistry, James B. Hendrickson, who developed a computer program for designing a synthesis based on sequences of generic "half-reactions". Computer-aided methods have recently been reviewed.^[5] Elias James Corey (born July 12, 1928) is an American organic chemist. ... Retrosynthetic analysis is a technique for solving problems in the planning of organic syntheses. ... List of Nobel Prize laureates in Chemistry from 1901 to the present day. ... Computational chemistry is a branch of theoretical chemistry whose major goals are to create efficient mathematical approximations and computer programs that calculate the properties of molecules (such as total energy, dipole and quadrupole moment, vibrational frequencies, reactivity and other diverse spectroscopic quantitities and cross sections for collision of molecules with...

See also

Organic Syntheses, a publication which gives detailed peer-tested laboratory procedures. Organic Syntheses is a scientific journal that Since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. ...

References

1. K. C. Nicolaou, E. J. Sorensen, Classics in Total Synthesis, VCH, New York, 1996.
2. R. B. Woodward, M. P. Cava, W. D. Ollis, A. Hunger, H. U. Daeniker, K. Schenker, Journal of the American Chemical Society 76, 4749 (1954).
3. J. March, D. Smith, Advanced Organic Chemistry, 5th ed., Wiley, New York, 2001.
4. E. J. Corey, X-M. Cheng, The Logic of Chemical Synthesis, Wiley, New York, 1995.
5. Matthew H. Todd, Computer-aided organic synthesis, Chemical Society Reviews, 34, 247-266 (2005). A very readable review available [online].

The Journal of the American Chemical Society (abbreviated usually as , or JACS), is a peer-reviewed scientific journal, published since 1879 by the American Chemical Society. ...

External links

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