Synthesis of chiral silver(I) diaminocarbene complexes from (R,R)-4,5-di-tert-butylimidazoline

A preparation of chiral silver(I) diaminocarbene complexes was developed by treatment of imidazolinium salts derived from (R,R)-4,5-di-tert-butylimidazoline with silver(I) oxide. Complexes having the chirality on the heterocycle and methyl, benzyl or picolyl groups on the nitrogen atoms have been prepared. We also performed the synthesis of diaminocarbenes having in addition the chiral (S)-1-phenylethyl moiety on the nitrogen atoms. X-ray structures of two of these carbenes (N,N′-dimethyl and N,N′-dibenzyl) are presented. Several methods for the preparation of imidazolinium salts are described.