- Cobalt-Catalyzed Cross-Benzannulation of Conjugated Enynes and Diynes
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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.
- R?se, Philipp,Garcia, Carmen Carlota Magraner,Pünner, Florian,Harms, Klaus,Hilt, Gerhard
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- Regioselective cobalt-catalyzed Diels-Alder reaction towards 1,3-disubstituted and 1,2,3-trisubstituted benzene derivatives
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A straightforward reaction sequence consisting of the Wittig olefmation of aldehydes utilizing allyltriphenylphosphonium bromide for the generation of 1-substituted 1,3-dienes, cobalt-catalyzed neutral Diels-Alder reaction with terminal and internal alkyn
- Hilt, Gerhard,Danz, Michael
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experimental part
p. 2257 - 2263
(2009/04/06)
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