Synthesis of substituted piperidines by enantioselective desymmetrizing intramolecular aza-Michael reactionsElectronic supplementary information (ESI) available: Experimental procedures, characterization data, HPLC traces of enantioenriched compounds and copies of 1H and 13C NMR spectra. CCDC 1829500. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8ob01139g

An organocatalytic enantioselective intramolecular aza-Michael reaction has been described for the first time in a desymmetrization process employing substrates different from cyclohexadienones. By using 9-amino-9-deoxy- epi -hydroquinine as the catalyst and trifluoroacetic acid as a co-catalyst, a series of enantiomerically enriched 2,5-and 2,6-disubstituted piperidines have been obtained in good yields and with moderate diastereoselectivity. Depending on the catalyst/co-catalyst loading ratio, either the major or the minor diastereoisomer of the final piperidine products was achieved with high levels of enantioselectivity. Finally, some mechanistic insights have been considered by means of theoretical calculations which were in agreement with the experimental results obtained in the desymmetrization reaction. An organocatalytic enantioselective intramolecular aza-Michael reaction has been described for the first time in a desymmetrization process employing substrates different from cyclohexadienones.