The Absolute Configuration of (+)-Ethyl cis-1-Benzyl-3-hydroxypiperidine-4-carboxylate and (+)-4-Ethyl 1-Methyl cis-3-Hydroxypiperidine-1,4-dicarboxylate; a Revision

Discrepancies between chiroptical data from the literature and our determination of the structure of the title compounds (+)‐5 and (+)‐9a were resolved by an unambiguous assignment of their absolute configuration. Accordingly, the dextrorotatory cis‐3‐hydroxy esters have (3R,4R)‐ and the laevorotatory enantiomers (3S,4S)‐configuration. The final evidences were demonstrated on both enantiomers (+)‐ and (−)‐5 by biological reduction of 4 by bakers' yeast and stereoselective [RuII(binap)]‐catalyzed hydrogenations of 4 (Scheme 2), by the application of the NMR Mosher method on (+)‐ and (−)‐5 (Scheme 3), as well as by the transformation of (+)‐5 into a common derivative and chiroptical correlation (Scheme 4).