Methyl isocyanoacetate ferrocenylphosphine-gold complexes

Table 11 Enantioselectivity and Diastereoselectivity in the Aldol Reactions of Methyl Isocyanoacetate Under Catalysis by Chiral Ferrocenylphosphine-Gold Complexes (equation 22)...

Asymmetric aldol reaction. In the presence of a gold(I) complex (1) and a chiral ferrocenylphosphine (2), various aldehydes react with methyl isocyanoacetate... 

Table 3. Diastereo- and enantioselective aldol reaction of methyl isocyanoacetate (27) with tildehydes catalyzed by chiral ferrocenylphosphine 86c gold(I) complex.

Ito and coworkers found that chiral ferrocenylphosphine-silver(I) complexes also catalyze the asymmetric aldol reaction of isocyanoacetate with aldehydes (Sch. 26) [51]. It is essential to keep the isocyanoacetate at a low concentration to obtain a product with high optical purity. They performed IR studies on the structures of gold(I) and silver(I) complexes with chiral ferrocenylphosphine 86a in the presence of methyl isocyanoacetate (27) and found significant differences between the iso-cyanoacetate-to-metal coordination numbers of these metal complexes (Sch. 27). The gold(I) complex has the tricoordinated structure 100, which results in high ee, whereas for the silver(I) complex there is an equilibrium between the tricoordinated structure 101 and the tetracoordinated structure 102, which results in low enantioselectivity. Slow addition of isocyanoacetate 27 to a solution of the silver(I) catalyst and aldehyde is effective in reducing the undesirable tetracoordinated species and results in high enantioselectivity. 

N-methyl-6-hydroxy-amino acids, such as the amino acid MeBmt (32). The aldol condensation of aldehydes with isocyanoacetate in the presence of a chiral ferrocenylphosphine-gold(I) complex afforded... 

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