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enter image description here My approach- Since a base is added the compound will release hydrogen ion.

My problem is from where will the ion be released? Benzene ring containing bromine is more activated than the other benzene ring. So it should be difficult to extract hydrogen ion from it. But I am getting my answer right by doing so. Shouldn't hydrogen be removed from the other benzene ring?
Also how do we know how many hydrogen ions will release? Is it necessary that only one hydrogen ion is released?

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  • $\begingroup$ The starting material will be heavily enolised. Consider the possible reaction pathways through the enolate, both through oxygen and carbon. $\endgroup$ – Waylander Feb 16 '18 at 9:38
  • $\begingroup$ @Waylander I can not understand which two pathways you mean. Please elaborate. $\endgroup$ – V J Feb 16 '18 at 9:58
  • $\begingroup$ The Hydrogen will be removed from the benzylic carbon.And the produced negative charge will delocalise through the carbonyl carbon and there will be high conjugation between two benzene rings and oxygen atoms can get negative charge. The reaction then might proceed through benzyne mechanism and Oxygen can attack as a nucleophile to form a penta cyclic compound . $\endgroup$ – Soumik Das Feb 16 '18 at 10:29
  • $\begingroup$ Re: "My problem is from where will the ion be released?" A proton will be released from the organic molecule. Since you're supposed to select the best proton, the resulting carbanion should be the most stable. At which position do you get the most stable carbanion here? $\endgroup$ – Gaurang Tandon Feb 16 '18 at 10:30
  • $\begingroup$ Consider reaction pathways through the oxygen of the enolate formed by reaction of the starting material and base, remember that intramolecular reactions are favoured over intermolecular. $\endgroup$ – Waylander Feb 16 '18 at 10:31

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