Cascade cyclization versus chemoselective reduction: a solvent-controlled product divergence

Abstract

A simple and efficient strategy for assembly of polysubstituted thiophenes as well as chemoselective reduction of α,β-unsaturated ketones via the reaction of enones with elemental sulfur and by simple switching...

Elemental Sulfur‐Promoted Synthesis of 4‐Hydroxybenzophenones from p‐Quinone Methides under Metal‐Free Condition

“…We employ the formation of 2 a as example to depict the mechanistic route of the reaction. Firstly, in the presence of base, the elemental sulfur undergoes a series of chemical transformations to form trisulfur radical anions (S 3 −• ) with the release of electrons [18a] . Subsequently, S 3 −• reacts selectively at δ position of 6‐arylated p ‐QMs 1 a to provide the radical anion intermediate A , which will isomerize quickly into intermediate B .…”

Synthesis of Substituted Thiophenes through Dehydration and Heterocyclization of Alkynols

“…2 Several approaches have been described, including the latestage modification of prefunctionalized thiophenes 3 or the production of substituted thiophenes from acyclic precursors via a transition metal-catalyzed reaction 4 or a radical-mediated method. 5 Numerous efficient procedures for the preferential synthesis of 2,5-disubstituted thiophenes have been described previously, including the sulfur annulation of 1,3-butadiynes or internal alkynes with trisulfur radical anions (S 3…”