Abstract
Treatment of 1,1′‐diacetylferrocene (4) with dimethylamine and TiCl~4~ yielded the unsaturated dimethylamino‐substituted [3]ferrocenophane product 5. Its catalytic hydrogenation gave the corresponding saturated [3]ferrocenophane system 6 (trans/cis ≈︁ 7:1). The rac‐[3]ferrocenophane amine 6 was partially resolved (to ca. 80% ee) by means of L‐ or D‐O,O′‐dibenzoyltartrate salt formation. Treatment of 4 with the pure (R)‐ or (S)‐methyl(1‐phenylethyl)amine (8)/TiCl~4~ gave the corresponding optically active unsaturated [3]ferrocenophane amines (R)‐(+)‐9 and (S)‐(−)‐9, respectively. Their catalytic hydrogenation again proceeded trans‐selectively, giving the corresponding saturated diastereomeric [3]ferrocenophane amines (1__R__,3__R__,5__R__)‐10a and (1__S__,3__S__,5__R__)‐10b [starting from (R)‐9], their enantiomers ent‐10a and ent‐10b were obtained from (S)‐9, but with a poor asymmetric induction (10a/10b < 2:1). Quaternization of 6 (CH~3~I) followed by amine exchange using (R)‐ or (S)‐methyl(1‐phenylethyl)amine (8), respectively, proceeded with overall retention. Subsequent chromatographic separation gave the pure diastereoisomers (1__R__,3__R__,5__R__)‐10a and (1__S__,3__S__,5__R__)‐10b [from (R)‐8, ent‐10a and ent‐10b from (S)‐8] in > 60% yield. Subsequently, the benzylic (1‐phenylethyl) auxiliary was removed from the nitrogen atom by catalytic hydrogenolysis to yield the enantiomerically pure (> 98%) ([3]ferrocenophanyl)methylamines (1__R__,3__R__)‐11 and (1__S__,3__S__)‐11, respectively, which were converted into the corresponding dimethylamino‐substituted [3]ferrocenophanes (1__R__,3__R__)‐6 and (1__S__,3__S__)‐6. Each enantiomer from the following enantiomeric pairs was isolated in its pure form and characterized by X‐ray diffraction: (R)‐9/(S)‐9; (1__R__,3__R__,5__R__)‐10a/(1__S__,3__S__,5__S__)‐10a; (1__R__,3__R__,5__S__)‐10b/(1__S__,3__S__,5__R__)‐10b; (1__R__,3__R__)‐11/(1__S__,3__S__)‐11. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)