[4+2] Cycloaddition Reaction of Cyclic Alkyne–{Co2(CO)6} Complexes with Dienes


  • This research was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.


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A general protocol for the title transformation has been achieved and is applicable to a wide range of acyclic 1,3-dienes and cyclic alkyne—{Co2(CO)6} complexes leading to various types of benzannulated medium-sized cyclic compounds after oxidative work up (see scheme; DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). Interestingly, the [4+2] cycloaddition proceeded preferentially over the Pauson–Khand reaction.