A new protocol for C-S bond formation was developed by selective cross-coupling between a thiyl radical and an isobutyronitrile radical. Using this strategy, a series of valuable α-alkylthionitrile derivatives were synthesized from basic starting materials. Preliminary mechanistic investigation was performed by EPR and XAFS, revealing that the transient thiyl radical could be stabilized by a copper catalyst to a persistent one. Therefore, on the basis of the persistent radical effect, selective radical-radical cross-coupling between the thiyl radical and the isobutyronitrile radical was achieved successfully in this work.
The manipulation of covalent bonds
could be directed toward degradable,
recyclable, and sustainable materials. However, there is an intrinsic
conflict between properties of stability and degradability. Here we
report light-controlled formation/scission of three types of covalent
bonds (C–N, C–O, and C–S) through photoswitching
between equilibrium and nonequilibrium states of dynamic covalent
systems, achieving dual benefits of photoaddressable stability and
cleavability. The photocyclization of dithienylethene fused aldehyde
ring–chain tautomers turns on the reactivity, incorporating/releasing
amines, alcohols, and thiols reversibly with high efficiency, respectively.
Upon photocycloreversion the system is shifted to kinetically locked
out-of-equilibrium form, enabling remarkable robustness of covalent
assemblies. Reaction coupling allows remote and directional control
of a diverse range of equilibria and further broadens the scope. Through
locking and unlocking covalent linkages with light when needed, the
utility is demonstrated with capture/release of bioactive molecules,
modification of surfaces, and creation of polymers exhibiting tailored
stability and degradability/recyclability. The versatile toolbox for
photoswitchable dynamic covalent reactions to toggle matters on and
off should be appealing to many endeavors.
Selective C-H bond activation and functionalization is an invaluable and eco-friendly tool for new chemical bond construction. Recently, great progress has been made in the highly selective ortho- and meta-C-H bond functionalization of arene derivatives. In contrast, the remote para-C-H bond functionalization still remains a challenge. Herein, an oxidation-induced strategy for para-selective C-H bond functionalization of iodobenzenes towards the synthesis of various useful asymmetric diaryl ethers was demonstrated. This strategy not only provides a novel method for para-C-H bond functionalization, but also proposes a general idea for the development of new, highly selective para-C-H functionalization reactions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.