Highly basic organometallic

The (dienyl)iron cations of type (248) and (265) are susceptible to reaction with nucleophiles. For the (cyclohexadienyl)iron cations, nucleophilic attack always occurs at a terminal carbon, on the face of the ligand opposite to the metal, to afford -cyclohexadiene products. Typical nucleophiles used are malonate anions, amines, electron-rich aromatics, silyl ketene acetals, enamines, hydrides, and allyl silanes intramolecular nucleophilic addition is also possible. The addition of highly basic organometallic nucleophiles (Grignard reagents, organolithiums) is often problematic this may be overcome by replacing one of the iron carbonyl... 

The basic organometallic reaction cycle for the Rh/I catalyzed carbonylation of methyl acetate is the same as for methanol carbonylation. However some differences arise due to the absence of water in the anhydrous process. As described in Section 4.2.4, the Monsanto acetic acid process employs quite high water concentrations to maintain catalyst stability and activity, since at low water levels the catalyst tends to convert into an inactive Rh(III) form. An alternative strategy, employed in anhydrous methyl acetate carbonylation, is to use iodide salts as promoters/stabilizers. The Eastman process uses a substantial concentration of lithium iodide, whereas a quaternary ammonium iodide is used by BP in their combined acetic acid/anhydride process. The iodide salt is thought to aid catalysis by acting as an alternative source of iodide (in addition to HI) for activation of the methyl acetate substrate (Equation 17) ... 

Organolithium compounds would be extremely desirable catalysts since the organometallic precursors such as alkyUithiums are readily available. It was found that intramolecular hydroamination of aminoalkenes can be mediated by a catalytic amount of -butyUithium [35, 106], The obvious drawback is the high basicity of lithium amides, which can result in double bond isomerization side reactions. Optimal conditions were found using a solvent mixture of THP and toluene at 1 lO C (3) although the reaction also proceeds at lower temperatures. 

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