Asymmetric Reformatsky Reaction with an Isoborneol Derivative Ligand

Significance

The high reactivity of Reformatsky reagents with aldehydes has impeded the development of successful enantioselective methods. (-)-DAIB was shown to be a good ligand for the enantioselective addition to various aldehydes. The best results were obtained with electron-rich aromatic aldehydes (72-93% ee) or with sterically hindered aliphatic aldehydes (66-92% ee). The addition of the difluorozinc reagent 4 also proceeded with high enantioselectivity (up to 90% ee). The enantioselectivity can be increased by using thiophene as additive (86-90% ee).