Development of Small-Molecule Fluorescent Probes Targeting Enzymes.

As biological catalysts, enzymes are vital in controlling numerous metabolic reactions. The regulation of enzymes in living cells and the amount present are indicators of the metabolic status of cell, whether in normal condition or disease. The small-molecule fluorescent probes are of interest because of their high sensitivity and selectivity, as well as their potential for automated detection. Fluorescent probes have been useful in targeting particular enzymes of interest such as proteases and caspases. However, it is difficult to develop an ideal fluorescent probe for versatile purposes. In the future, the design and synthesis of enzyme-targeting fluorescent probes will focus more on improving the selectivity, sensitivity, penetration ability and to couple the fluorescent probes with other available imaging molecules/technologies.

Regioselective Fluoroalkylphosphorylation of Unactivated Alkenes by Radical-Mediated Alkoxyphosphine Rearrangement.

A novel distal radical rearrangement of alkoxyphosphine is developed for the first time and applied to the regioselective radical fluoroalkylphosphorylation of unactivated olefins. By employing a one-pot two-step reaction of (bis)homoallylic alcohols, organophosphine chlorides, and fluoroalkyl iodides under CFL (compact fluorescence light) irradiation, a series of fluoroalkylphosphorylated alkyl iodides and alcohols are easily synthesized by regiospecific installing a phosphonyl onto the inner carbon of terminal olefins and further iodination/hydroxylation. Mechanism studies reveal that the migration undergoes a distinctive radical cyclization/ß-scission on the lone electron pair of phosphorus, resulting in C-P bond formation and C-O bond cleavage.

Electrochemically Tuned Oxidative [4+2] Annulation and Dioxygenation of Olefins with Hydroxamic Acids.

This work represents the first [4+2] annulation of hydroxamic acids with olefins for the synthesis of benzo[c][1,2]oxazines scaffold via anode-selective electrochemical oxidation. This protocol features mild conditions, is oxidant free, shows high regioselectivity and stereoselectivity, broad substrate scope of both alkenes and hydroxamic acids, and is compatible with terpenes, peptides, and steroids. Significantly, the dioxygenation of olefins employing hydroxamic acid is also successfully achieved by switching the anode material under the same reaction conditions. The study not only reveals a new reactivity of hydroxamic acids and its first application in electrosynthesis but also provides a successful example of anode material-tuned product selectivity.