A metal-free four-component sulfonylation, Giese cyclization, selenylation cascade via insertion of sulfur dioxide

Abstract

We hereby report a highly regio- and diastereoselective arylsulfonylation-radical cyclization-selenylation cascade of alkynyl cyclohexadienones for the facile synthesis of highly functionalized dihydrochromenones. The protocol utilizes aryldiazonium salts as aryl partners...

Regioselective Radical Cascade Cyclizations of Alkyne-Tethered Cyclohexadienones with Chalcogenides under Visible-Light Catalysis

“… 22 Very recently, while this manuscript was under preparation, Volla and co-workers also demonstrated a multicomponent radical cascade reaction for the synthesis of highly functionalized dihydrochromenones using explosive aryldiazonium salts as aryl partners and expensive DABSO as a SO 2 source and also as a redox mediator under reflux conditions ( Scheme 1 ,D). 22 , 23 …”

“…Later, Xu developed a three-component tandem cyclization/substitution for the construction of highly substituted dihydrochromenones using cyclohexadienones, diselenides, and H 2 O (Scheme ,C) . Xu and colleagues reported the cascade cyclization of alkyne-tethered cyclohexadienones, although they employed a presynthesized starting material where the preparation required reflux temperature and a pricey hypervalent reagent (Scheme ,D) . Very recently, while this manuscript was under preparation, Volla and co-workers also demonstrated a multicomponent radical cascade reaction for the synthesis of highly functionalized dihydrochromenones using explosive aryldiazonium salts as aryl partners and expensive DABSO as a SO 2 source and also as a redox mediator under reflux conditions (Scheme ,D). , …”

“…22 Very recently, while this manuscript was under preparation, Volla and co-workers also demonstrated a multicomponent radical cascade reaction for the synthesis of highly functionalized dihydrochromenones using explosive aryldiazonium salts as aryl partners and expensive DABSO as a SO 2 source and also as a redox mediator under reflux conditions (Scheme 1,D). 22,23 Inspired by these results and our previous experience on photoredox catalysis, 24 we envisioned that sulfonyl radicals generated from sulfonyl hydrazides or sodium sulfinates might be added to alkynyl cyclohexadienones and undergo Giesetype cyclization, followed by selenation by diselenides to produce bis-functionalization (Scheme 1,E) (see Scheme 1).…”

Diphenyl Ditelluride: An Unconventional Reducing Agent in the Sulfonylative Cascade of Alkynyl Cyclohexadienones

“…Recently, alkynyl cyclohexadienones due to the presence of two reactive π-systems, viz., alkyne and enone, have emerged as imaginative building blocks for accessing a wide variety of heterocycles. , Our group has previously engaged alkynyl cyclohexadienones as key starting materials in divergent metal- or radical-mediated cyclizations . While cascade cyclizations of alkynyl cyclohexadienones involving monofunctionalization have been well studied, the corresponding more challenging difunctionalizations has been much less explored.…”