Iron-catalyzed reactions carbometalation

Reaction of the resulting cyclopropylmetal derivatives with different electrophiles provided diastereomerically enriched products 123 in good yields [34]. Catalytic processes promoted by transition metals are powerful synthetic tools for the selective formation of carbon-carbon bonds including carbometallation processes. Thus, a highly diastereoselective iron-catalyzed carbometallation of oxa- and azabicycloalkenes with arylzinc reagents was reported recently by Nakamura et al. 

Another example of the iron-catalyzed carbometallation reaction of unactivated alkynes was reported for the aryknagnesiation of alkyl(aryl)acetylenes [64b]. The addition of arylmagnesium bromide to the disubstituted aryl(alkyl)alkynes 234 was found to proceed efficiently in the presence of Fe(acac)j as a catalyst and a substoichiometric amount of an N-heterocyclic carbene (NHC) ligand (IPr) as an additive, which significantly increased the yield of this carbometallation process (Scheme 10.79). 

Iron-Catalyzed Addition Reactions 3.4.1 Carbometalation of Aikynes... 

---