Applications of benzene formation

Benzo-type heterocyclic compounds can be prepared by this method. There have been many examples of this type of reaction using various metals, as shown in Eq. 2.54 [7qJ. 

Benzo-type heterocycle formation from zirconacyclopentadienes. 

Metalated benzene derivatives can also be prepared by the reaction of alkynyl lithium reagents with zirconacyclopentadienes (Eq. 2.55) [39]. 

Further carbon—carbon bond formation on the benzene ring is possible and the reaction can be catalytic when an Ni metal oxidation step is introduced, as shown in Eq. 2.56 [40], 

R alkyl, R = alkyl Eq 2.56. Benzene formation from zirco-82 50-55% nacyclopentadienes catalyzed by Ni. 

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