An Unprecedented Retro-Mumm Rearrangement Revealed by ESI-MS/MS, IRMPD Spectroscopy, and DFT Calculations.
Claudio IacobucciSamantha RealeMassimiliano AschiJos OomensGiel BerdenFrancesco De AngelisPublished in: Chemistry (Weinheim an der Bergstrasse, Germany) (2018)
Brønsted acids and protic solvents mediate acyl transfer, known as the Mumm rearrangement, from imidates to the corresponding acylamides. This represents a key step in several reactions, for example, the Ugi four-component reaction (U-4CR) and Passerini three-component reaction (P-3CR). Herein, an unprecedented break of the non-reversibility of the Mumm rearrangement is reported. A combination of electrospray tandem mass spectrometry (ESI-MS/MS), infrared multiphoton dissociation (IRMPD) ion spectroscopy and theoretical calculations demonstrates the occurrence of the retro-Mumm rearrangement of protonated isopeptides in the gas phase. In the gas phase, the extra proton acquired during ESI promotes the backward isomerisation reaction in a catalytic fashion.
Keyphrases
- ms ms
- ultra high performance liquid chromatography
- electron transfer
- tandem mass spectrometry
- density functional theory
- ionic liquid
- high performance liquid chromatography
- liquid chromatography
- high resolution
- liquid chromatography tandem mass spectrometry
- molecular dynamics
- mass spectrometry
- molecular dynamics simulations
- single molecule
- gas chromatography
- high resolution mass spectrometry
- risk assessment
- solid phase extraction
- molecular docking