The Bergman cyclization or Bergman reaction or Bergman cycloaromatization is an organic reaction and more specifically a rearrangement reaction taking place when an enyne is heated in presence of a suitable proton donor (Scheme 1). The reaction product is a derivative of benzene. Organic reactions are chemical reactions between organic compounds. ... A rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. ... In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound that is a colorless and flammable liquid with a pleasant, sweet smell. ...

The reaction proceeds by a thermal reaction or pyrolysis (above 200°C) forming a short-lived and very reactive para-benzyne diradical species. It will react with any proton donor such as 1,4-cyclohexadiene which converts to benzene. When quenched by tetrachloromethane the reaction product is a 1,4-dichlorobenzene and with methanol the reaction product is benzyl alcohol. Simple sketch of pyrolysis chemistry Pyrolysis usually means the chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam. ... Wikipedia does not have an article with this exact name. ... 1,4-Cyclohexadiene is a hydrocarbon and a cyclic alkene and polyene. ... Carbon tetrachloride CCl4 is a synthetic chemical compound formerly widely used in fire extinguishers and refrigeration, but now largely abandoned due to its toxicity. ... R-phrases , , S-phrases , , , , Flash point 66 °C RTECS number CZ4550000 Supplementary data page Structure and properties n, εr, etc. ... Methanol, also known as methyl alcohol or wood alcohol, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a very faint odor. ... Benzyl alcohol, also known as phenylmethanol, is a clear, colorless liquid with a mild pleasant aromatic odor. ...

When the enyne moiety is incorporated into a 10-membered hydrocarbon ring (e.g. cyclodeca-3-ene-1,5-diyne in scheme 2) the reaction, taking advantage of increased ring strain in the reactant, is possible at the much lower temperature of 37°C. Ring strain is an organic chemistry term that describes the destabilization of a cyclic molecule—such as a cycloalkane—due to the non-favorable high energy spatial orientations of its atoms. ...

Naturally occurring compounds exist containing the same 10-membered enyne ring and are found to be cytotoxic. These compounds generate the diradical intermediate described above which cause single- and double stranded DNA cuts. Novel drug research attempts to make use of this property ^[1]. Cytotoxicity is the quality of being poisonous to cells. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ... Oral medication Caffeine is the most widely used psychoactive substance in the world. ...

External links

• Bergman Cycloaromatization Powerpoint Whitney M. Erwin 2002

References

1. ↑  p-Benzyne. Generation as an intermediate in a thermal isomerization reaction and trapping evidence for the 1,4-benzenediyl structure Richard R. Jones, Robert G. Bergman J. Am. Chem. Soc.; 1972; 94(2); 660-661. Abstract
2. ↑  Design and synthesis of heterocycle fused enediyne prodrugs activable at willLuca Banfi, Andrea Basso, Giuseppe Guanti, and Renata Riva Arkivoc 2006 HL-1786GR 261-275 Abstract