Catalytic Enantioselective Aza-Reformatsky Reaction with Cyclic Imines

A catalytic highly enantioselective aza-Reformatsky reaction with cyclic aldimines and ketimines for the synthesis of chiral b-amino esters with good yields and excellent enantioselectivities is reported.Areadily available diaryl prolinol is used as a chiral ligand, ZnMe2 as a zinc source and ethyl iodoacetate as reagent in the presence of air atmosphere. The reaction with cyclic ketimines generates a quaternary stereocenter with excellent levels of enantioselectivity. Furthermore, five-membered N-sulfonyl ketimines were used as electrophiles with good enantiomeric excesses, under the optimized reaction conditions. Moreover, several chemical transformations were performed with the chiral b-amino esters.
Financial support from the MINECO (Gobierno de Espana; CTQ2013-47494-P). L.D.M. thanks the Generalitat Valenciana for a predoctoral grant. C.V. thanks MINECO for a JdC contract. Access to NMR, MS and X-ray facilities from the Servei central de suport a la investigacio experimental (SCSIE)-UV is also acknowledged.