Acyl radicalsa re invaluablei ntermediates in organic synthesis, however theirg eneration remains challenging.H erein, we presenta nu nprecedented light-driven, cobalt-catalysed method for the generation of acyl radicals from readilya vailable 2-S-pyridyl thioesters.T he synthetic potential of this methodology was demonstrated in the Giese-type acylation of activatedo lefinsi nt he presence of heptamethylc obyrrinate.T his vitaminB 12 derivative provedtobethe most efficient catalyst in the studied process.T he developedm ethod featuresb road sub-strate scope (38 examples), good functional group tolerance,a nd mild reactionc onditions.M oreover, it is easily scalable( illustrated on a2 0-folds cale-up procedure), enabling its preparative use.M echanistic studies revealedt hat the reactionp roceeds via ar adical pathway with the key steps involving the formation of an acyl-vitamin B 12 complexa nd subsequent photolysis of the Co À Cb ond.

A series of molecular salts of the antimalarial drug pyrimethamine (PYR) with salicylic acid (SA) and its methyl-substituted derivatives 3-methylsalicylic acid (3Me-SA), 4-methylsalicylic acid (4Me-SA), and 5-methylsalicylic acid (5Me-SA) was obtained. Additionally, cocrystallization of PYR with the structural analogues of SA 3-hydroxybenzoic acid (3OH-BA) and 4-hydroxybenzoic acid (4OH-BA) led in the case of 3OH-BA to the formation of a molecular salt, while cocrystallization with 4OH-BA did not lead to the formation of an associate of any kind. In all obtained crystal structures, the carboxylate anion interacts with the protonated at N1 pyrimethamine moiety in a linear fashion through a pair of parallel N–H···O hydrogen bonds forming a cyclic hydrogen-bonded motif. In the crystal structure of PYR-SA as well as in the structures involving methylated derivatives of SA (3Me-SA, 4Me-SA, and 5-Me-SA), a typical PYR-PYR association via a pair of N–H···N bonds between the N(4)­H2 amino group of one molecule and the N3 unsubstituted amino atom of the second PYR molecule is observed, a motif that is characteristic of two known PYR polymorphs. On the other hand, in the structure of PYR-3OH-BA, the PYR-PYR connection is realized via a pair of N–H···N bonds between the N(2)­H2 amino group of one molecule and the N3 unsubstituted amino atom of the second PYR molecule. In all of the structures, chlorine atoms are involved in C–H···Cl interactions with either the acid molecule or another PYR moiety, while in the structure of PYR-3Me-SA molecules are additionally connected through halogen Cl···Cl interactions. All of the obtained structures were thoroughly characterized by single-crystal X-ray analyses, Hirshfeld analyses, DFT calculations, and thermal analyses (TGA and DSC).

Precise and stimuli-controllable transport of charged and neutral guests is a hallmark of cellular processes. Although ion transport has been mimicked with artificial carriers, no such systems are known for electrically neutral ion pairs. We have engineered an artificial carrier (1) that demonstrates a regulated binding and transport of ion pairs dependant on the photo-controlled translocation of the cation and anion binding domains. The NMR and electrochemical experiments supported by DFT calculations show that UVA-generated V-shaped cis-1, featuring ion binding domains close to each other, exhibits an unprecedented 74-fold higher extraction rate of ion pairs relative to the native trans-1.