Asymmetric Titanium-Catalyzed Cyclopropanation of Nitriles with Grignard Reagents

The titanium-catalyzed asymmetric cyclopropanation of cyanoesters with Grignard reagents was investigated for the first time. Particularly, the study of the efficiency of Taddol-based titanium complexes has shown that the prior preparation of Taddol titanium complexes was not required and a large panel of ligands was evaluated by using this approach. The spirocyclopropanelactams were obtained with good diastereoselectivity and with moderate enantioselectivities from the main diastereoisomer (up to 32%).