MeCAAC=N-: A Cyclic (Alkyl)(Amino)Carbene Imino Ligand

A cyclic (alkyl)(amino)carbene (CAAC) has been shown to react with a covalent azide similar to the Staudinger reaction. The reaction of (Me)CAAC with trimethylsilyl azide afforded the N-silylated 2-iminopyrrolidine ((Me)CAAC=NSiMe3), which was fully characterized. This compound undergoes hydrolysis to afford the 2-iminopyrrolidine and trimethylsiloxane which co-crystallize as a hydrogen-bonded adduct. The N-silylated 2-iminopyrrolidine was used to transfer the novel pyrrolidine-2-iminato ligand onto both main-group and transition-metal centers. The reaction of the tetrabromodiborane bis(dimethyl sulfide) adduct with two equivalents of (Me)CAAC=NSiMe3 afforded the disubstituted diborane. The reaction of (Me)CAAC=NSiMe3 with TiCl4 and CpTiCl3 afforded (Me)CAAC=NTiCl3 and (Me)CAAC=NTiCl2Cp, respectively.