Universität Düsseldorf: Investigations on Novel 1,3-Diazetidine Based Four-Membered N-Heterocyclic Carbenes

27.02.2023 | 08:00

Novel four-membered NHCs containing a carbamide backbone rapidly form the respective carbene dimers in quantitative yield. Thermal fragmentations are rationalized with the help of quantum chemical calculations.

Attempts towards the synthesis of two novel four-membered 1,3-diazetidine based N-heterocyclic carbenes (NHCs) containing an organic backbone with a carbonyl functionality were undertaken. These carbenes cannot be isolated but the respective carbene dimers are obtained in quantitative yield which undergo a degradation and rearrangement sequence upon thermal exposure. Some of the species involved in these thermal reactions could be isolated and characterized, others were observed by mass spectrometric experiments. Ab initio and density functional theory (DFT) calculations provide a mechanistic rationale for the experimental observations. Since dimerization is strongly favored, classic carbene trapping reactions remain a goal to achieve.