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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/08/09 09:29:00」(JST)
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In chemistry, regioselectivity is the preference of one direction of chemical bond making or breaking over all other possible directions.[1][2] It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base will abstract from an organic molecule, or where on a substituted benzene ring a further substituent will add.
A specific example is a halohydrin formation reaction with 2-propenylbenzene:[3]
Because of the preference for the formation of one product over another, the reaction is selective. This reaction is regioselective because it selectively generates one constitutional isomer rather than the other.
Certain examples of regioselectivity have been formulated as rules for certain classes of compounds under certain conditions, many of which are named. Among the first introduced to chemistry students are Markovnikov's rule for the addition of protic acids to alkenes, and the Fürst-Plattner rule for the addition of nucleophiles to derivatives of cyclohexene, especially epoxide derivatives.[4][5]
Regioselectivity in ring-closure reactions is subject to Baldwin's rules. If there are two or more orientations that can be generated during a reaction, one of them is dominant (e.g., Markovnikov/anti-Markovnikov addition across a double bond)
Regioselectivity can also be applied to specific reactions such as addition to pi ligands.
Selectivity also occurs in carbene insertions, for example in the Baeyer-Villiger reaction. In this reaction an oxygen is regioselectively inserted near an adjacent carbonyl group. In ketones this insertion is directed toward the carbon which is more highly substituted (i.e. according to Markovnikov's rule). For example, in a study involving acetophenones this oxygen was preferentially inserted in-between the carbonyl and the aromatic ring to give acetyl aromatic esters, not methyl benzoates.[6]
See also
- Zaitsev's rule
- Cryptoregiochemistry
- Chemoselectivity
- Stereoselectivity
- Enantioselectivity
- Keto–enol tautomerism
References
- ^ March, Jerry (1985), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (3rd ed.), New York: Wiley, ISBN 0-471-85472-7
- ^ http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch06/ch6-0-1.html Regioselectivity & Stereoselectivity
- ^ Regioselectivity in Organic Synthesis: Preparation of the Bromohydrin of alpha-Methylstyrene Brad Andersh, Kathryn N. Kilby, Meghan E. Turnis, and Drew L. Murphy 102 Journal of Chemical Education • Vol. 85 No. 1 January 2008
- ^ W. Markownikoff (1870). "Ueber die Abhängigkeit der verschiedenen Vertretbarkeit des Radicalwasserstoffs in den isomeren Buttersäuren". Annalen der Pharmacie 153 (1): 228–259.
- ^ Fürst, A.; Plattner, P. A. Helv. Chim. Acta 1949, 32, 275
- ^ Palmer, Billy W.; Fry, Arthur (1970). "Variation of carbon-14 isotope effect with substituent and the mechanism of the m-chloroperbenzoic acid oxidation of laeled para-substituted acetophenones". Journal of the American Chemical Society. 92 (8): 2580–2581. doi:10.1021/ja00711a079.
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Topics in Organic Reactions
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- Addition reaction
- Elimination reaction
- Polymerization
- Reagents
- Rearrangement reaction
- Redox reaction
- Regioselectivity
- Stereoselectivity
- Stereospecificity
- Substitution reaction
- List of organic reactions
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English Journal
- Influence of intramolecular hydrogen bonds on regioselectivity of glycosylation. Synthesis of lupane-type saponins bearing the OSW-1 saponin disaccharide unit and its isomers.
- Kuczynska K1, Cmoch P1, Rárová L2, Oklešťková J3, Korda A1, Pakulski Z4, Strnad M5.
- Carbohydrate research.Carbohydr Res.2016 Mar 24;423:49-69. doi: 10.1016/j.carres.2016.01.010. Epub 2016 Jan 26.
- A series of lupane-type saponins bearing OSW-1 disaccharide unit as well as its regio- and stereoisomers were prepared and used for the structure-activity relationships (SAR) study. Unexpected preference for 1→4-linked regioisomers and an unusual inversion of the conformation of the sugar rings we
- PMID 26878488
- Organo-Iodine(III)-Catalyzed Oxidative Phenol-Arene and Phenol-Phenol Cross-Coupling Reaction.
- Morimoto K1,2, Sakamoto K1, Ohshika T1, Dohi T1, Kita Y3,4.
- Angewandte Chemie (International ed. in English).Angew Chem Int Ed Engl.2016 Mar 7;55(11):3652-6. doi: 10.1002/anie.201511007. Epub 2016 Feb 16.
- The direct oxidative coupling reaction has been an attractive tool for environmentally benign chemistry. Reported herein is that the hypervalent iodine catalyzed oxidative metal-free cross-coupling reaction of phenols can be achieved using Oxone as a terminal oxidant in 1,1,1,3,3,3-hexafluoropropan-
- PMID 26879796
- A Study on the Photoreaction of 2(5H)-Furanones with Substituted Acetylenes: Evidence for a Mechanistic Reformulation.
- Flores R1, Font J1, Alibés R2, Figueredo M3.
- Chemistry (Weinheim an der Bergstrasse, Germany).Chemistry.2016 Mar 7;22(11):3835-45. doi: 10.1002/chem.201503888. Epub 2016 Jan 8.
- The photoreaction of 2(5H)-furanones with alkynes has been investigated. The complexity of this process is evidenced by the variety of isolated products, which have allowed disclosing interesting mechanistic aspects. When the reaction is performed in acetonitrile under direct excitation, in addition
- PMID 26749319
Japanese Journal
- ニッケル(0)錯体によるビシクロ[1.1.0]ブタン誘導体とアクリル酸メチルの反応におけるジェミナル二結合開裂の位置選択性
- 遷移金属ヒドリド触媒による有機ラジカル種の発生と有機合成への利用
- イナミドを用いた多置換エナミドの位置および立体選択的合成
Related Links
- Alkene Stability & Regioselectivity, E1 Elimination: regioselectivity and stereoselectivity, E2 Elimination: regioselectivity, Regiochemistry, Regioselectivity and Regiospecificity, Regioselectivity of Free Radical Halogenation ... How to ...
- Definition of regioselectivity in the Definitions.net dictionary. Meaning of regioselectivity. What does regioselectivity mean? Information and translations of regioselectivity in the most comprehensive dictionary definitions resource on the ...
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