A Chiral, Oxidatively Cleavable Auxiliary in β-Lactam Synthesis - Double Diastereocontrol with p-Methoxyphenethyl-Substituted Imines

All articles of this category A new chiral, oxidatively removable auxiliary for the Staudinger reaction is presented. When diazo ketones 1-3 prepared from suitably protected amino acids reacted with p -methoxyphenethyl (PMPE)-substituted imines, the corresponding trans -substituted β-lactams 7 and 8a-h were formed. With the ( S )-configured imine 5 , an improvement of the selectivities is observed in comparison with achiral p -methoxybenzyl (PMB)-substituted imines by double stereoselection; consequently, the ratio of isomers decreased with the ( R )-imine 4 . The auxiliary could be removed with cerium ammonium nitrate (CAN). protecting groups - double stereoinduction - β-lactam synthesis - diazo ketones - imines