Synthesis Of 3-Acetyl-/V-Aryl-4-Diethylamino-Selenet-2(2h)-Imines From 4-Diethylamino-3-Butyn-2-One And Aryl Isoselenocyanates

摘要

The reaction of aryl isoselenocyanates (1a-d) with 4-diethyl-amino-3-butyn-2-one (6) in refluxing tetrahydrofuran afforded N-arylselenet-2(2H)-imines (7) in moderate yields. The structure of the stable 4-bromophenyl derivative (7b) has been established by X-Ray crystallography. A stepwise cycloaddition via an intermediate zwitterion (A/A') is proposed as the reaction mechanism. In boiling tetrahydrofuran, the selenetimines (7) are in equilibrium with ketenimines (B), which were intercepted by amines to give 2-(diaminomethylene)-3-oxobutane selenamides of type (8).