Palladium-Catalysed Spiro-Cyclisation of Substituted Amino Acids with Maleimides via γ-C(sp³)-H Bond Activation

Achieving the site-selective functionalization of unactivated C(sp³)-H bonds remains a major challenge in organic synthesis. Herein, we report an efficient method for the synthesis of spiro pyrrolidine molecules via the γ-C(sp³)-H bond activation of substituted amino acids. A variety of amino acid and amino alcohol derivatives, as well as dipeptides, were functionalized using this method. Also, spirocyclization of optically active substrates provided a potential route for preparing separable diastereomers in pure enantiomeric form. Moreover, some mechanistic insights have been conducted to propose a feasible reaction mechanism for the present spirocyclization reaction.