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Cobalt-Catalyzed Cross-Benzannulation of Conjugated Enynes and Diynes.

Research paper by Philipp P Röse, Carmen Carlota Magraner CC Garcia, Florian F Pünner, Klaus K Harms, Gerhard G Hilt

Indexed on: 19 Jun '15Published on: 19 Jun '15Published in: Journal of Organic Chemistry



Abstract

The [4 + 2] cross-benzannulation of conjugated enynes and diynes under cobalt-catalysis led to 1,2,3-trisubstituted benzene derivatives in good yields. The reaction proceeds smoothly in absolute regiospecific control when symmetrical diynes are applied. Moreover, the use of unsymmetrical diynes was investigated, resulting in the formation of the unprecedented regioisomers as major products, which is in contrast to the results obtained in palladium-catalyzed benzannulation reactions. Also, 4-bromophenyl-substituted starting materials could be applied successfully in the cobalt-catalyzed process, which can be problematic in the palladium-catalyzed counterpart.