Preparation of Optically Active α‐Amino[3]ferrocenophanes − Building Blocks for Chelate Ligands in Asymmetric Catalysis

Abstract

, their enantiomers ent-10a and ent-10b were obtained from (S)-9, but with a poor asymmetric induction (10a/10b Ͻ 2:1). Quaternization of 6 (CH 3 I) followed by amine exchange using (R)-or (S)-methyl(1-phenylethyl)-

Preparation of Enantiomerically Pure [3]Ferrocenophane‐Based Chelate Bis‐Phosphane Ligands and Their Use in Asymmetric Alternating Carbon Monoxide/Propene Copolymerization

“…For additional general information, including a list of the instruments used for physical characterization of the compounds see refs. [6,14] . The starting materials rac-3, (R,R)-3 and (S,S)-3 were prepared as described previously by us in the literature.…”

“…The starting materials rac-3, (R,R)-3 and (S,S)-3 were prepared as described previously by us in the literature. [14] For the atom numbering Scheme used for the NMR listings, see Scheme 2. Most NMR assignments were secured by additional 2D NMR experiments.…”

“…We had previously shown that the (6R,9R)-3 and (6S,9S)-3 enantiomers were rather easily available on a preparative scale, using methyl(1-phenylethyl)amine as a chiral auxiliary, and employing a simple chromatographic separation of the respective diastereomers. [14] After hydrogenolytic removal of the auxiliary followed by N-methylation, each of the enantiomers of 3 was obtained in ca. 30 % overall yield (of a possible max.…”

quart‐Feproline: Synthesis of a Very Rigid [3]Ferrocenophane‐Derived Artificial Amino Acid

“…The α-dimethylamino group can be exchanged for the (S)-phenylethylamino chiral auxiliary [8] by quaternization (with MeI) followed by exchange with (S)-phenylethylamine. This two-step exchange reaction proceeds with overall retention of configuration at the α-position of the [3]ferrocenophane bridge.…”

Unusual carbamate-directed CH-activation at an annulated ferrocenophane framework

“…Both started from the a-dimethylamino substituted [3]ferrocenophane derivative rac-5 11 which was readily available by an intramolecular Mannich condensation reaction of 1,1¢diacetylferrocene with dimethylamine followed by catalytic hydrogenation as we had previously described. [12][13][14][15] We then subjected 5 to a directed lithiation with tert.-butyllithium followed by treatment with DMF to yield the formyl derivative 6 after hydrolysis (see Scheme 3).…”