Highly stable atropisomers by electrophilic amination of a chiral γ-lactam within the synthesis of an elusive conformationally restricted analogue of α-methylhomoserine

Starting from chiral-protected 4-hydroxymethyl pyrrolidin-2-ones, the otherwise elusive 3,4-trans-3,3,4-trisubstituted isosteres of alpha-methyl homoserine, tethered on a gamma-lactam ring, were prepared exploiting stereoselective electrophilic aminations. These reactions led to the isolation and characterization of a novel type of atropisomers, exceedingly stable at room temperature, that were directly converted to the desired products by a novel non-reductive N-N bond cleavage reaction.