1,3-Bis(N,N-dialkylamino)imidazolin-2-ylidenes: Synthesis and Reactivity of a New Family of Stable N-Heterocyclic Carbenes

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Abstract
The synthesis of stable 1,3-bis(N,N-dialkylamino)imidazolin-2-ylidenes was accomplished from readily available chiral bis-hydrazones after reduction or addition of PhMgCl, cyclization to imidazolinium salts, and treatment with KN(SiMe3)2. This strategy allows the obtention of free imidazolin-2-ylidenes and their Rh(COD)Cl complexes in enantiomerically pure form. The σ-donor ability of dialkylamino-substituted diaminocarbenes was found to be slightly higher than that of alkyl(aryl) analogues.