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Chemistry LibreTexts

17.4: Concerted Addition of Electrophiles to π Bonds with Formation of 4-Membered Ring Transition States

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  • The electrophile E-Y can also approach the C=C π-bond in such a way that both E and Y bond to each of the two carbons simultanesouly. This requires the formation of a four-membered ring transition state and necessarily results in net syn addition of E-Y to the π-bond.


    The hydroboration-oxidation (addition of water using via borane) is an example of this outcome.