Visible-Light-Promoted Xanthate-Transfer Cyclization Reactions of Unactivated Olefins under Photocatalyst- and Additive-Free Conditions

Abstract

A general visible-light-induced photocatalyst-/additive-free strategy was developed for the construction of various nitrogen-heterocycles (42 examples, up to 97% yield) such as γ-lactams, δ-lactams, pyrrolidines, indolones, quinolinones, and fused polycyclic structures at room temperature. The prominent features of this protocol are mild and environmentally friendly conditions, broad substrate scope, and good functional group tolerance. Importantly, the reaction can be performed under natural sunlight, the most sustainable energy source imaginable. Furthermore, this strategy provides straightforward access to a range of derivatives through subsequent elaboration of the xanthate group.

Photocatalysis as a green alternative toolkit for the construction of nitrogen-enriched heterocycles via the direct and indirect activation of alkynes/alkenes

“…Recently, Chen and group developed a photoinduced migratory insertion reaction-based cyclization reaction (Table 15A and B). 95 In this study, several nitrogen-heterocycles, including lactams, pyrrolidines, indoles, quinolinones, and fused polycyclic structures, were constructed in up to 97% yield at room temperature using 42 examples. Here, the nitrogen-rich cyclic derivatives ( 538 / 539 / 542 / 543 ) were produced by photoinitiation, followed by C–S bond cleavage, cyclization, and rearrangement of O -ethyl carbonodithioate attachment.…”

Radical Cyclization-Initiated Difunctionalization Reactions of Alkenes and Alkynes

“…Chen and Wang and coworkers, in 2022, introduced a xanthate-involved ATRC reaction of unactivated olefins for the synthesis of various nitrogen heterocycles such as γ -lactams, δ -lactams, pyrrolidines, indolones, quinolinones, and fused polycyclic compounds. The reaction of N -xanthylamides 146 in CH 2 Cl 2 under the irradiation of 24 W 400 nm LEDs at room temperature gave products 147 or 148 in good to excellent yields ( Scheme 35 ) [ 61 ]. It is worth mentioning that the xanthate-transfer reaction proceeded without photo-catalyst and additive.…”

Light‐Induced Domino and Multicomponent Reactions: How to Reach Molecular Complexity without a Catalyst

“…γ‐Lactams, δ‐lactams in addition to pyrrolidines, indolones, quinolinones, and fused polycyclic were obtained by N ‐xanthylamides 59 bearing an un‐activated olefins by the simple action of a purple LED in CH 2 Cl 2 under photocatalyst‐/additive‐free conditions (Scheme 23). [40] The key of the process was a cascade xanthate transfer‐cyclization. Forty‐two examples were reported with yields up to 97 %, and good functional group tolerance.…”