Stereoselective construction of contiguous stereogenic centers of acyclic compounds by using the Fe(CO)3 moiety as a mobile chiral auxiliary is described. Although the reactions of acyclic (pentadienyl)iron(1+) cations with nucleophiles generally occur in a stereoselective but nonregioselective manner, giving rise to several regioisomers, O-acyl and O-phosphoryl cyanohydrin Fe(CO)3 complexes 2−5 undergo regio- and stereoselective 1,5-nucleophilic substitution with several heteroatomic nucleophiles, giving the 6-substituted hepta-2,4-dienonitrile Fe(CO)3 complexes 6 and 7, that is, 1,2-migration products of the Fe(CO)3 group. These products were obtained as single products, even if the starting materials 3−5 were a mixture of diastereomers. The (2E,4E)/(2E,4Z) selectivity of the 1,5-substituted products (6/7) is strongly dependent on the Lewis acid catalyst, triphenylcarbenium perchlorate (TrClO4) giving 6 (method A) and BF3·etherate giving 7 (method B), respectively. Furthermore, by applying iterative 1,5...