Example：10.1021/acsami.1c06204 or Chem. Rev., 2007, 107, 2411-2502
General stereoretentive preparation of chiral secondary mixed alkylmagnesium reagents and their use for enantioselective electrophilic aminations Chemical Science (IF9.825), Pub Date : 2021-10-19, DOI: 10.1039/d1sc05315a Alexander Kremsmair, Henrik R. Wilke, Matthias M. Simon, Quirin Schmidt, Konstantin Karaghiosoff, Paul Knochel
A general preparation of enantiomerically and diastereomerically enriched secondary alkylmagnesium reagents was reported as well as their use for performing highly stereoselective transition-metal free electrophilic aminations leading to α-chiral amines in up to 97% ee. Thus, the reaction of t-BuLi (2.2 equiv.) with a mixture of chiral secondary alkyl iodides and the commercially available magnesium reagent Me3SiCH2MgCl in a 2 : 1 mixture of pentane and diethyl ether at up to −50 °C provided optically enriched secondary mixed alkylmagnesium species of the type alkyl(Me)CHMgCH2SiMe3 with high retention of configuration (up to 99% ee). The resulting enantiomerically enriched dialkylmagnesium reagents were trapped with electrophiles such as non-enolizable ketones, aldehydes, acid chlorides, isocyanates, chlorophosphines and O-benzoyl hydroxylamines providing α-chiral tertiary alcohols, ketones, amides, phosphines and tertiary amines in up to 89% yield (over three reaction steps) and up to 99% ee.