Zum stereochemischen Verlauf der elektrophilen Substitution an CH‐Gruppen in α‐Stellung zum N‐Atom behinderter Amide Vorläufige Mitteilung

On the Sterochemical Course of Electrophilic Substitution at CH Groups in α‐Position to the N‐Atom of Hindered Amides It is shown by 1 H‐NMR. analysis of the aminoalcohol derivatives 4b and 4c that the lithiation/hydroxyalkylation with acetone of 1‐nitroso‐and 1‐(2,4,6‐triiso‐propylbenzoyl)‐4‐phenyl‐piperidine leads to configurationally different products. The assigned cis and trans configuration of the substituents in 4b and 4c , respectively, is compatible with the electronic structures 2 and 1 , respectively, which were previously proposed for the lithio‐derivatives 3 involved in such transformations.