MeCN highly coordinating solvent

Intramolecular amidopalladation has also been used in the construction of isoin-dolinones (110) from hydroxamic derivatives (109). In the presence of ligand (111), the product was obtained in <99% ee. The use of MeCN as a highly coordinating solvent (ff) proved to be essential. ... 

Whilst metallocenes have an enormously rich chemistry, in the case of arene coordination it is the half-sandwich ( piano-stool ) class of complex which finds the widest utility in organic synthesis, in particular within the chemistry of Cr(CO)3(ti6-arene) complexes. These are generally prepared directly from the thermal reaction of Cr(CO)6 and arene in a high-boiling solvent (e.g. Bu20, 2-picoline). For less robust arenes, the labile complexes Cr(L)3(CO)3 (L = NH3, THF, MeCN, py) may be employed under milder conditions (Figure 7.38). 

Since strong acids are formed, the reaction must be carried out in the presence of bases. Coordinating and polar solvents, such as DMF, MeCN, NMP and DMSO, are preferable solvents. DMF is the most widely used. Water, a highly polar liqvud, has been found to accelerate some reactions, which are carried out smoothly in aqueous solvents using water-soluble ligands. 

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