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Such reactions are said to be anti-Markovnikov, since the halogen adds to the less substituted carbon, the opposite of a Markovnikov reaction. The anti-Markovnikov rule can be illustrated using the addition of hydrogen bromide to isobutylene in the presence of benzoyl peroxide or hydrogen peroxide. The reaction of HBr with substituted alkenes ...
Hydroboration–oxidation is an anti-Markovnikov reaction, with the hydroxyl group attaching to the less-substituted carbon. The reaction thus provides a more stereospecific and complementary regiochemical alternative to other hydration reactions such as acid-catalyzed addition and the oxymercuration–reduction process.
For terminal olefins (or acetylenes), the regioselectivity of the process can be described as Markovnikov (addition of X at the substituted end) or anti-Markovnikov (addition of X at the unsubstituted end). Catalysts are frequently employed to control the chemo-, regio-, and stereoselectivity of hydrofunctionalization reactions.
This process utilizes anti addition of an OH group to the more substituted carbon, making this reaction a Markovnikov reaction. Alkyne hydroboration-oxidation: In this reaction, a disiamylborane reaction, disiamylborane is added to one face of the triple bond. The boron atom attaches to the less substituted carbon, and later forms a bond ...
[3]: 188, 751 The result is typically anti-Markovnikov addition, a phenomenon Morris Kharasch called the "peroxide effect". [4] Reaction is slower with alkynes than alkenes. [3]: 750 In the paradigmatic example, hydrogen bromide radicalyzes to monatomic bromine. These bromine atoms add to an alkene at the most accessible site, to give a ...
Free-radical additions can be initiated by light, heat or radical initiators, which form a thiyl radical species. The radical then propagates with an ene functional group via an anti-Markovnikov addition to form a carbon-centered radical. A chain-transfer step removes a hydrogen radical from a thiol, which can subsequently participate in ...
Anti-Markovnikov selectivity is also observed in styrenyl substrates (i.e. Figure 3, C), [39] presumably via η 4-palladium-styrene complex after water attacks anti-Markovnikov. More examples of substrate-controlled, anti-Markovnikov Tsuji-Wacker Oxidation of olefins are given in reviews by Namboothiri, [40] Feringa, [36] and Muzart. [41]
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