Proton-bound complex mediating retro-Michael type fragmentation of protonated bicyclic caprolactams in the Orbitrap HCD cell

摘要

In the fragmentation of protonated dicyclic caprolactams, a retro-Michael reaction was observed. Theoretical calculations demonstrated that this retro-Michael reaction only takes place when the external proton migrates from the most thermodynamically favorable protonation site to the dissociative protonation site by a four-member ring transition state. Moreover, the kinetic plot of ln([a]/[b]) versus the differences in proton affinities of two corresponding neutral molecules is a straight line, indicating that this retro-Michael reaction proceeds via the proton-bound complex [c...H~+...d] intermediate. This study would be potential for further understanding the reactive activities of dicyclic caprolactams.