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In organic chemistry, syn-and anti-addition are different ways in which substituent molecules can be added to an alkene (R 2 C=CR 2) or alkyne (RC≡CR).The concepts of syn and anti addition are used to characterize the different reactions of organic chemistry by reflecting the stereochemistry of the products in a reaction.
In organic chemistry, the oxymercuration reaction is an electrophilic addition reaction that transforms an alkene (R 2 C=CR 2) into a neutral alcohol. In oxymercuration, the alkene reacts with mercuric acetate (AcO−Hg−OAc) in aqueous solution to yield the addition of an acetoxymercury (−HgOAc) group and a hydroxy (−OH) group across the ...
The rule makes no generalizations about the stereochemistry of the newly formed alkene, but only the regiochemistry of the elimination reaction. While effective at predicting the favored product for many elimination reactions, Zaytsev's rule is subject to many exceptions.
The addition of Grignard reagents to alkynes is facilitated by a catalytic amount of copper halide. Transmetalation to copper and carbocupration are followed by transmetalation of the product alkene back to magnesium. The addition is syn unless a coordinating group is nearby in the substrate, in which case the addition becomes anti and yields ...
The addition of singlet carbenes to alkenes is stereospecific in that the geometry of the alkene is preserved in the product. For example, dibromocarbene and cis-2-butene yield cis-2,3-dimethyl-1,1-dibromocyclopropane, whereas the trans isomer exclusively yields the trans cyclopropane. [4]
For many years, the stereochemistry of the Wittig reaction, in terms of carbon-carbon bond formation, had been assumed to correspond directly with the Z/E stereochemistry of the alkene products. However, certain reactants do not follow this simple pattern. Lithium salts can also exert a profound effect on the stereochemical outcome. [8]
Addition of a carbene to an alkene to form a cyclopropane. One of the most synthetically important cheletropic reactions is the addition of a singlet carbene to an alkene to make a cyclopropane (see figure at left). [1] A carbene is a neutral molecule containing a divalent carbon with six electrons in its valence shell.
Alkyl and aryl terminal alkenes react with high regioselectivity to give 5-substituted isoxazolidines. This outcome is consistent with frontier molecular orbital (kinetic) control of the distribution of isomers: the nitrone oxygen, which possesses the largest orbital coefficient in the HOMO of the nitrone, forms a bond with the inner carbon of the alkene, which possesses the largest orbital ...