Synthesis of enantiopure pyrrolidine and piperidine derivatives via ring closing metathesis

The additions of lithiated allylsulfone carbanion to chiral N-sulfinylimines were found to proceed with good to excellent selectivity. The resulting intermediates 4a–d after transformation to dienylamides 7a–d and 16a–d, were converted to functionalized enantiopure piperidines and pyrrolines, respectively, via ring closing metathesis (RCM).