Carbene complexes, tetracarbonyl phosphine

The anions generated from tetracaibonyl(phosphine) carbene complexes are more reactive in their reactions with organic electrophiles. This is consistent with the observation that the p/iTa of the methyl pentacarbonyl complex (88a) is increased by six orders of magnitude when one of the carbon monoxi ligands is replaced with tributylphosphine. The anion generated fr-om (106) will give good yields of alkylated products with simple alkyl halides such as ethyl bromide however, dialkylation is still a serious side reaction. It has been reported that both pentacarbonyl and tetracarbonyl(phosphine) complexes can be efficiently monoalkylated with alkyl triflates (primary and secondary). The anion (89) for example, can be monoalkyated with the 3-butenyl triflate in 80% yield. ... 

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