Palladium-Mediated Synthesis of a Near-Infrared Fluorescent K+ Sensor

Potassium (K+) exits electrically excitable cells during normal and pathophysiological activity. Currently, K+-sensitive electrodes and electrical measurements are the primary tools to detect K+ fluxes. Here, we describe the synthesis of a near-IR, oxazine fluorescent K+ sensor (KNIR-1) with a dissociation constant suited for detecting changes in intracellular and extracellular K+ concentrations. KNIR-1 treatment of cells expressing voltage-gated K+ channels enabled the visualization of intracellular K+ depletion upon channel opening and restoration of cytoplasmic K+ after channel closing.

4,4′-Bismoschamine: biomimetic synthesis and evidence to support structural equivalency to montamine

A biomimetic synthesis of 4,4′-bismoschamine enabled comparison of its NMR data to dimeric tryptamines, which supports structural equivalency to montamine.

Total synthesis of putative montamine and a proposed structural reassignment

The spectroscopic data for synthetic montamine does not match the proposed N,N′-linked structure and closely resembles a known 4,4′-bismoschamine natural product.