Collect. Czech. Chem. Commun.
2003, 68, 1206-1232
https://doi.org/10.1135/cccc20031206
Synthesis and Catalytic Activity of Spaced Ferrocene Oxazolines
Petr Štěpničkaa,*, Tomáš Bašea, Ivana Císařováa, Jiří Kubištab, Štěpán Vyskočilc and Martin Štíchac
a Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
b J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic
c Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic
Abstract
Chiral 2-[{N-aryl-N-(ferrocenylmethyl)amino}methyl]-4-(1-methylethyl)-4,5-dihydroxazoles with various substituents at the aryl ring were prepared by alkylation of N-(ferrocenylmethyl)anilines, FcCH2NHC6H4R (Fc = ferrocenyl), with (S)-2-(chloromethyl)-4-(1-methylethyl)-4,5-dihydrooxazole. The oxazoles, substituted anilines, and the precursors of the latter, the respective Schiff bases FcCH=NC6H4R, were characterized by standard methods and further studied by mass spectrometry. The oxazoles were further tested as chiral auxiliaries in the addition of diethylzinc to benzaldehyde but showed only negligible asymmetric induction (ee ca 10%), most likely due to steric hindrance of the nitrogen donor centres. This steric restriction seems to be lowered upon replacement of the substituted phenyl group with a benzyl substituent; compounds FcCH2NHCH2Ph and (R)-FcCH2NHCH(Me)Ph are easily alkylated yielding [FcCH2NMe2(CH2Ph)]I (9) and 2-[{N-(1-phenylethyl)-N-(ferrocenylmethyl)amino}methyl]-4-(1-methylethyl)-4,5-dihydroxazole (10), respectively. Solid-state structures of FcCH2NHC6H4R (R = 2-Me and 4-Cl), 9, and 10 have been determined by single-crystal X-ray diffraction.
Keywords: Oxazolines; Ferrocenes; Mass spectrometry; Organozinc reagents; Enantioselective catalysis; Crystal structure; Chiral ligands; Schiff bases; Imines; Amines; X-Ray diffraction.
References: 49 live references.
