13 C-NMR-untersuchungen an substituierten cycloalkenen : I. Trimethylsilylenolether

The ¹³C-NMR spectra of the cyclic silyenolethers 1a-i are discussed with regard to the electron density within the carbon ring skeleton, conformation of the trimethylsilyloxy substituent and configuration of the double bond in higher membered ringsystems.     

Manganese‐Catalyzed Carbonylative Annulations for Redox‐Neutral Late‐Stage Diversification

An inexpensive, nontoxic manganese catalyst enabled unprecedented redox‐neutral carbonylative annulations under ambient pressure. The manganese catalyst outperformed all other typically used base and precious‐metal catalysts. The outstanding versatility of the manganese catalysis manifold was reflected by ample substrate scope, setting the stage for effective late‐stage manipulations under racemization‐free conditions of a wealth of marketed drugs and natural products, including alkaloids, amino acids, steroids, and carbohydrates.     

FRET Monitoring of Intracellular Ketal Hydrolysis in Synthetic Nanoparticles

Degradable synthetic crosslinking is a versatile strategy to harness nanomaterials against disassembly in a complex physiological medium prompted by dilution effects or competitive interaction. In particular, chemical bonds such as ketals that are stable at physiological conditions but are cleaved in response to disease‐mediated or intracellular conditions (e.g., a mildly acidic pH) are of great relevance for biomedical applications. Despite the range of spectroscopic or chromatographic analyses methods that allow chemical degradation in solution to be assessed, it is much less straightforward to interrogate synthetic nanomaterials for their degradation state when located inside a living organism. We demonstrate a method based on FRET analysis to monitor intracellular disassembly of block‐copolymer‐derived nanoparticles engineered with a FRET couple on separate polymer chains, which after self‐assembly are covalently crosslinked with a pH‐sensitive ketal‐containing crosslinker.