Chiral Selenide-Catalyzed, Highly Regio- and Enantioselective Intermolecular Thioarylation of Alkenes with Phenols

Abstract

Enantioselective electrophilic three-component thioarylation of alkenes by chiral selenide catalysis with free phenols as arylating sources is disclosed. A variety of chiral phenols were achieved in high regio-, enantio-, and diastereoselectivities. Mechanistic studies revealed that this transformation went through carbon nucleophilic attack to give the products rather than the process of intramolecular rearrangement of phenolic ether intermediates. The application of this organocatalytic method in the alkylation of methoxy-substituted benzenes elucidated its generality.

Nickel-catalyzed para-selective carboxylation of phenols with CBr4/MeOH

“…A recent example of this transformation is the Friedel–Crafts type of electrophilic substitution reaction. 4 Recently, visible-light-promoted photoredox catalysis via single electron transfer provided a new approach. 5 Recently, the Phipps and Maleczka groups disclosed the para -selective C–H borylation of phenol substrates via ion-pair electrostatic interactions.…”

Chiral Chalcogenide-Catalyzed Enantioselective Electrophilic Hydrothiolation of Alkenes

“…They can also serve as organocatalysts and ligands, which have broad applications in organocatalysis and transition-metal catalysis . Therefore, developing simple and efficient methods for preparing chiral sulfides has become an intriguing area. − Among the developed methods, catalytic hydrothiolation of alkenes is particularly appealing because of the easy availability of alkenes and the synthetic advantages. ,, In this scenario, considerable efforts have been devoted to constructing chiral sulfides with special alkenes and nucleophilic sulfur reagents. For example, enantioselective sulfa-Michael additions of thiols to electron-deficient alkenes via either organocatalysis or metal catalysis have been demonstrated (Scheme b, top left). , As a complementary strategy, rhodium-catalyzed enantioselective hydrothiolation of allenes, conjugated dienes, and cyclopropenes with thiols has also been reported recently (Scheme b, top right) .…”

Catalytic Electrophilic Thiocarbocyclization of Allenes

“…Their structural motifs are found in a wide range of biologically active molecules and drugs. , They can serve as building blocks for the synthesis of valuable compounds and also act as ligands and organocatalysts in organic reactions. , Due to their importance, numerous methods have been developed to construct these compounds via metal catalysis and organocatalysis in the past several decades. , For example, transition metal-catalyzed cross-coupling of alkenyl halides with sulfur compounds as well as catalytic hydrothiolation of alkynes to synthesize alkenyl sulfides has been demonstrated . In particular, as a facile route, catalytic electrophilic thiolation of unsaturated hydrocarbon compounds to construct sulfides has attracted a great deal of attention. ,− This kind of reaction can be carried out under mild and metal-free conditions. When utilizing electrophilic sulfur reagents, the reactions generally go through a thiiranium or thiirenium ion intermediate, followed by attack of the nucleophiles to give the final sulfide products, which offers a convenient method for quickly constructing multifunctionalized sulfur compounds.…”

“…When utilizing electrophilic sulfur reagents, the reactions generally go through a thiiranium or thiirenium ion intermediate, followed by attack of the nucleophiles to give the final sulfide products, which offers a convenient method for quickly constructing multifunctionalized sulfur compounds. In this scenario, the thiolation of alkenes and alkynes has been studied (Scheme , top). − In contrast, the thiolation of allenes, unsaturated compounds with unique structural features, including orthogonal π-orbitals composed of sp 2 and sp carbons, has been rarely investigated (Scheme , bottom) . To the best of our knowledge, only oxy- and halothiolation of allenes have been demonstrated.…”

“…The Lewis basic selenium-catalyzed electrophilic reaction has emerged as an intriguing strategy for the synthesis of various valuable molecules. − ,, In this reaction, Lewis basic selenium compounds can activate electrophilic halogen or sulfur reagents to form a selenium-captured cation ion intermediate. The intermediate has a proper reactivity and can lead to less side products compared with the solo electrophile E + ion.…”