Bioorthogonally activated reactive species for target identification

A target identification platform derived from the bioorthogonal activation of reactive species is described. We explore the reactivity of halogenated enamine N-oxides and report that the previously undisclosed α,γ-halogenated enamine N-oxides can be reduced biooorthogonally by diboron reagents to produce highly electrophilic α,β-unsaturated haloiminium ions suitable for labeling a range of amino acid residues on proteins in a 1,2- or 1,4-fashion. Affinity labeling reagents bearing this motif enable ligand-directed protein modification and afford highly sensitive and selective target identification in unbiased chemoproteomics experiments. Target identification is supported in both cell lysate and live cells.

Synthesis of Structurally Diverse 3-, 4-, 5-, and 6-Membered Heterocycles from Diisopropyl Iminomalonates and Soft C-Nucleophiles

Herein, we present a general synthetic strategy for the preparation of 3-, 4-, 5-, and 6-membered heterocyclic unnatural amino acid derivatives by exploiting facile Mannich-type reactions between readily available N-alkyl- and N-aryl-substituted diisopropyl iminomalonates and a wide range of soft anionic C-nucleophiles without using any catalyst or additive. Fully substituted aziridines were obtained in a single step when enolates of α-bromo esters were employed as nucleophiles. Enantiomerically enriched azetidines, γ-lactones, and tetrahydroquinolines were obtained via a two-step catalytic asymmetric reduction and cyclization sequence from ketone enolate-derived adducts. Finally, highly substituted γ-lactams were prepared in one pot from adducts obtained using acetonitrile-derived carbanions. Overall, this work clearly demonstrates the utility of iminomalonates as highly versatile building blocks for the practical and scalable synthesis of structurally diverse heterocycles.