S−H⋅⋅⋅π Driven Anti‐Markovnikov Thiol‐Yne Click Reaction

Abstract

Herein we demonstrate that an anti-Markovnikov selective thiol-yne-click (TYC) reaction could be achieved between phenyl acetylenes and thiophenols by exploiting a newly identified SÀ H···π non-covalent interaction without using any catalysts, additives and solvents. Natural bond orbital (NBO) analyses also supported that SÀ H···π and cooperative π-π stacking interactions helped to promote this regioselective reaction. The hydrothiolated products were isolated in near quantitative yields. Also, the concept of selfsorting was demonstrated when styrene, phenyl acetylene and thiophenols were reacted in one pot. Owing to the stronger SÀ H···π preference of ethynyl � H over the vinyl = H hydrogen bond, selectively, TYC product formation was found to be dominating over the thiol-ene-click (TEC) product.

Thiol-yne click reaction: an interesting way to derive thiol-provided catechols

“…The thiol-yne click (TYC) reaction, also known as alkyne hydrothiolation, is one of the simplest and most atomeconomical approach to produce alkenyl suldes from thiols and alkynes. 4,5 The TYC reaction commonly occurs in the presence of free radicals, 6 strong acids, 7 bases 8 or transition metals 9 and, as shown in Scheme 1, in principle can lead to one of the regio-and stereoisomeric vinyl suldes: A (branched) through a Markovnikov orientation, B (E linear) and C (Z linear), or produce mixtures of them through an anti-Markovnikov orientation (Scheme 1). 10,11 Regardless of the method used to promote the reaction, it is important to bear in mind that both alkyne and thiol groups are inherently nucleophilic, hence the activation of one or both groups is necessary for the construction of vinyl suldes.…”

Iodine(III) Enabled Dehydrogenative Aryl C−S Coupling by in situ Generated Sulfenium Ion

“…Due to normal polarity preferences the π‐electrons of arenes and hydrogens of thiols prefer hydrogen bonding or S−H⋅⋅⋅π interaction,,, which inhibit direct aryl C−S coupling (Figure a). However, using umpolung reactivity of sulfur, we have shown here that direct C−S coupling was possible via generation of sulfenium ion and subsequent utilization of them for aromatic electrophilic substitution (EArS) reactions (Figure b).…”

Thiol−Ene Reaction: Synthetic Aspects and Mechanistic Studies of an Anti‐Markovnikov‐Selective Hydrothiolation of Olefins

“…On the other hand, thiols have also been proven as an inexpensive starting material for synthesis of thioether via thiol‐ene reaction and allylic rearrangement, and thus expected to be the greenest route towards formation of C−S bond ,…”