Optically Active Transition Metal Complexes. 130. 1 Synthesis, Crystal Structures, and Catalytic Properties of Chiral-at-Metal (η 6 -Arene)ruthenium(II) and (η 6 -Arene)osmium(II) Half-Sandwich Complexes. Crystallization of Pure Diastereomers versus Diastereomer Mixtures in a 1:1 Ratio
2003; American Chemical Society; Volume: 22; Issue: 8 Linguagem: Inglês
10.1021/om020964u
ISSN1520-6041
AutoresHenri Brunner, Thomas Zwack, Manfred Zabel, Wolfgang Beck, Andreas Böhm,
Tópico(s)Asymmetric Synthesis and Catalysis
ResumoCondensation of a number of optically active amines and α-amino acid esters with salicylaldehyde gave the chiral compounds HLL*-1−HLL*-8. A series of diastereomeric complexes of the type (RM,SC)- and (SM,SC)-[(η6-arene)M(LL*)X] (1−14: M = Ru, Os; X = Cl, I), differing only in the metal configuration, were formed by reaction of [(η6-arene)MCl2]2 with these compounds in the presence of base and by halogen exchange. Five of the complexes were characterized by X-ray structure analyses. Three cases showed the structural peculiarity that the single crystals contained the RM,SC and SM,SC diastereomers with opposite configurations at the metal centers in a 1:1 ratio, whereas two cases crystallized as pure RM,SC diastereomers. Two complexes, the ligands of which (the salicylaldiminates of methyl phenylalaninate and methyl phenylglycinate) had racemized during the synthesis, crystallized as racemates RRu,SC/SRu,RC. Complexes 1−14 were tested as catalysts in the enantioselective isomerization of 2-n-butyl-4,7-dihydro-1,3-dioxepin to give 2-n-butyl-4,5-dihydro-1,3-dioxepin. Enantioselectivities up to 64% ee were achieved.
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