Compounds of formula I can be obtained by assembling the aminopyrrolidine derivatives of formula 16-1 with a ketone of formula 16-2 by reductive amination using a reducing agent such as sodium triacetoxyborohydride or through hydrogenation followed by treating the resulting secondary amine 16-3 via reductive amination with an aldehyde or by alkylation with an alkyl halide (RX).