A robust, generally applicable, nongenetic technology is presented to convert monoclonal antibodies into stable and homogeneous ADCs. Starting from a native (nonengineered) mAb, a chemoenzymatic protocol allows for the highly controlled attachment of any given payload to the N-glycan residing at asparagine-297, based on a two-stage process: first, enzymatic remodeling (trimming and tagging with azide), followed by ligation of the payload based on copper-free click chemistry. The technology, termed GlycoConnect, is applicable to any IgG isotype irrespective of glycosylation profile. Application to trastuzumab and maytansine, both components of the marketed ADC Kadcyla, demonstrate a favorable in vitro and in vivo efficacy for GlycoConnect ADC. Moreover, the superiority of the native glycan as attachment site was demonstrated by in vivo comparison to a range of trastuzumab-based glycosylation mutants. A side-by-side comparison of the copper-free click probes bicyclononyne (BCN) and a dibenzoannulated cyclooctyne (DBCO) showed a surprising difference in conjugation efficiency in favor of BCN, which could be even further enhanced by introduction of electron-withdrawing fluoride substitutions onto the azide. The resulting mAb-conjugates were in all cases found to be highly stable, which in combination with the demonstrated efficacy warrants ADCs with a superior therapeutic index.

The asymmetric Mannich reaction ranks among the most potent enantioselective and diastereoselective C-C-bond forming reactions. In recent years, organocatalysed versions of asymmetric Mannich processes have been increasingly reported and used in a rapidly growing number of applications. This tutorial review provides an overview of the recent history of the asymmetric organocatalysed Mannich reaction, including scope and limitations, and application of different catalyst systems.

Visualizing biomolecules by fluorescent tagging is a powerful method for studying their behaviour and function inside cells. We prepared and genetically encoded an unnatural amino acid (UAA) that features a bicyclononyne moiety. This UAA offered exceptional reactivity in strain-promoted azide-alkyne cycloadditions. Kinetic measurements revealed that the UAA reacted also remarkably fast in the inverse-electron-demand Diels-Alder cycloaddition with tetrazine-conjugated dyes. Genetic encoding of the new UAA inside mammalian cells and its subsequent selective labeling at low dye concentrations demonstrate the usefulness of the new amino acid for future imaging studies.

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The synthesis of enantiopure molecules from achiral precursors without the need for pre-existing chirality is a major challenge associated with the origin of life. We here show that an enantiopure product can be obtained from achiral starting materials in a single organic reaction. An essential characteristic of this reaction is that the chiral product precipitates from the solution, introducing a crystal–solution interface which functions as an asymmetric autocatalytic system that provides sufficient chiral amplification to reach an enantiopure end state. This approach not only provides more insight into the origin of life but also offers a pathway to acquire enantiopure compounds for industrial applications.