The envisaged cascade proceeds through an initial enzymatic reductive amination of the diketone substrate, followed by the spontaneous cyclisation of the N-alkyl ketoamine intermediate to the respective pyrrolinium cation, which undergoes further enzymatic reduction affording the desired N-alkylated pyrrolidine. As shown in Scheme 7, this proposed transformation would again mirror our previous TA-IRED work , with the key difference of a single enzyme catalysing the full cascade.