With the substrate scope thoroughly scrutinized, a series of mechanistic experiments is then carried out (Schemes 4 and 5). The enaminone as a whole is Indeed, quantitative characterization for a reaction between 6 and 2a informs amine-imine group exchange as the shared first step, as the combined yields of 3aa (35%) and 5 (33%) are approximately equal to that of substitution side product HNPh 2 (70%). An insight into the olefin-imine metathesis process is gained by the isolation of PhCN (29%) as a side product, along with 3aa (34%), when reacting 7 with 2a. Consistent with the amine-imine group exchange proposition, alkyne-containing 8, which can undergo hydroimination reaction, is also capable of reacting with 2a to afford 3aa (26%; as well as 69% of 5). This can be viewed as an alkyne-imine metathesis reaction. by the reductive elimination; however, the oxidation state ambiguity can always exist for this type of organometallic transformation) and re-generation of i, ring fragmentation of iv and the delivery of 3aa (as well as side product HCN).