The in vitro performance of some of the new tetrazine probes turned out to be comparable to the established lead probe [Lu]Lu-DOTA-PEG-Tz ([Lu]4). However, tumor pretargeting studies in vivo showed lower tumor uptake and increased uptake in non-target organs.

A stereodivergent synthesis of the first examples of 4-membered carbasugars has been achieved from vitamin C by way of an efficient intramolecular SmI2-mediated aldehyde-alkene coupling. In this key step, cylobutanes with four contiguous asymmetric centers are generated with a high level of stereocontrol.