[CpCo(CO)2] catalyzes the cycloisomerization of 1,n-enynes to afford selectively five- and six-membered ring systems in high yields. The factors governing the cyclization have been explored and we have discovered that the reaction associates two different, but complementary, reactivities of the cobalt(I) complexes. By a judicious choice of the substitution of the enyne, it was also possible to isolate
Novel reactivity of enynes in presence of cobalt (I) complexes
作者:Dominique Llerena、Corinne Aubert、Max Malacria
DOI:10.1016/0040-4039(96)01723-6
日期:1996.10
1,7- and 1,8-enynes led to five-membered carbocycles in presence of CpCo(CO)2. Free ligands and η4 -cobalt complexes have been isolated and characterized. A mechanism for this new cobalt-mediated cycloisomerization involving selective cobalt allylic CH activation is proposed.