Abstract
Mannich condensation of 1,1′-diacetylferrocene with dimethylamine followed by catalytic hydrogenation gives the chiral α-dimethylamino[3]ferrocenophane. Both enantiomers are available by resolution. Directed ortho -lithiation/iodination yields the ortho -iodo-α-dimethylamino[3]ferrocenophane derivative, whose treatment with acetic anhydride and copper(I) oxide yielded the mono- and diacetoxy-functionalized derivatives. The ortho -phosphorylated α-dimethylamino systems (-PPh2 , -PCy2 ) underwent exchange of the directing NMe2 group with NH2 by means of an ammonolysis reaction of the corresponding α-chloride derivatives, which in turn were obtained by treatment of the α-dimethylamino compounds with methylchloroformate. Starting from α-dimethylamino[3]ferrocenophane, the sequence of directed ortho -lithiation (t -BuLi), treatment with p -tosyl azide/sodium pyrophosphate (to yield the ortho -azido[3]ferrocenophane derivative) followed by catalytic hydrogenation gave the ortho -amino and α-dimethylamino[3]ferrocenophane derivatives. The potential use of some of the chelate ferrocenophane ligands in Ru-catalyzed asymmetric hydrogenations was investigated. Seven of the newly synthesized compounds were characterized by X-ray diffraction.
Key words
ferrocene - chelate ligand - amino group - P,N-ligand - asymmetric hydrogenation - catalysis
