SuFEx-enabled,chemoselective synthesis of triflates,triflamides and triflimidates

Sulfur(vi) Fluoride Exchange (SuFEx) chemistry has emerged as a next-generation click reaction, designed to assemble functional molecules quickly and modularly. Here, we report the ex situ generation of trifluoromethanesulfonyl fluoride (CF₃SO₂F) gas in a two chamber system, and its use as a new SuFEx handle to efficiently synthesize triflates and triflamides. This broadly tolerated protocol lends itself to peptide modification or to telescoping into coupling reactions. Moreover, redesigning the S^VI–F connector with a S O → S NR replacement furnished the analogous triflimidoyl fluorides as SuFEx electrophiles, which were engaged in the synthesis of rarely reported triflimidate esters. Notably, experiments showed H₂O to be the key towards achieving chemoselective trifluoromethanesulfonation of phenols vs. amine groups, a phenomenon best explained—using ab initio metadynamics simulations—by a hydrogen bonded termolecular transition state for the CF₃SO₂F triflylation of amines.

Triflyl fluoride gas (CF₃SO₂F) and its aza analogues are reported as new SuFEx activators. These S^VI–F reagents react efficiently with a variety of nucleophiles, yet the presence of water grants complete chemoselectivity to phenols.     

Orientational phenomena in comb-shaped liquid crystal polymers induced by laser beam irradiation

Action of the laser illumination on optical properties of liquid crystalline (LC) comb-shaped acrylic and methacrylic copolymers containing cyanobiphenyl mesogenic groups and azo dye fragments has been studied. Under an illumination the cis-trans configurational changes of dye fragments take place and reorientation of the side groups towards a direction perpendicular to the electric vector of the actinic light occurs. As a result the photoinduced optical birefringence (δn = 0.05-0.11) appears. The detailed study of dichrotic and optical properties of polymeric films, kinetics and relaxation of δn, as well as mechanism of orientational transformations during a laser illumination are discussed. The induced optical anisotropy of the films can be changed reversibly by rotating the electric vector of the laser beam in respect to the film that may be used in reversible optical data storage.