Alkene <i>versus</i> alkyne reactivity in unactivated 1,6-enynes: regio- and chemoselective radical cyclization with chalcogens under metal- and oxidant-free conditions

Mutra, Mohana Reddy; Kudale, Vishal Suresh; Li, Jing; Tsai, Wu-Hsun; Wang, Jhi-Joung

doi:10.1039/d0gc00321b

Cited by 74 publications

(37 citation statements)

References 70 publications

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“…Recently, an intramolecular version of 5‐exo cyclization was employed in the synthesis of selenium‐functionalized pyrrolidines and chromenones [63,64] . For the synthesis of the pyrrolidine derivatives 153 , several unactivated 1,6‐enynes 151 were treated with benzenesulfonoselenoates or diaryl diselenides 152 (Scheme 37), affording the corresponding cyclized products in moderate to excellent yields [63] . Regarding the 1,6‐enynes 151 , the reaction works well with terminal and internal alkynes, so only internal alkenes can were used.…”

Section: Cyclizationmentioning

confidence: 99%

Light‐Mediated Seleno‐Functionalization of Organic Molecules: Recent Advances

Rafique

Rampon

Azeredo

et al. 2021

The Chemical Record

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Organoselenium compounds constitute an important class of substances with applications in the biological, medicinal and material sciences as well as in modern organic synthesis, attracting considerable attention from the scientific community. Therefore, the construction of the C−Se bond via facile, efficient and sustainable strategies to access complex scaffolds from simple substrates are an appealing and hot topic. Visible light can be regarded as an alternative source of energy and is associated with environmentally‐friendly processes. Recently, the use of visible‐light mediated seleno‐functionalization has emerged as an ideal and powerful route to obtain high‐value selenylated products, with diminished cost and waste. This approach, involving photo‐excited substrates/catalyst and single‐electron transfer (SET) between substrates in the presence of visible light has been successfully used in the versatile and direct insertion of organoselenium moieties in activated and unactivated C(sp3)−H, C(sp2)−H, C(sp)−H bonds as well as C−heteroatom bonds. In most cases, ease of operation and accessibility of the light source (LEDs or commercial CFL bulbs) makes this approach more attractive and sustainable than the traditional strategies.

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Section: Cyclizationmentioning

confidence: 99%

Light‐Mediated Seleno‐Functionalization of Organic Molecules: Recent Advances

Rafique

Rampon

Azeredo

et al. 2021

The Chemical Record

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“…A variety of propargyl pyridines and diorganyl diselenides were screened, and a wide range of 2-(organoselenyl)-indolizine 33 were obtained in generally good yields. Notably, when propargyl pyridines was equipped with a terminal alkyne, the indolizine with two phenyl selenium groups in the structure (34) was obtained in 30% yield. However, employing dibutyl diselenide as organoselenium source, the desired product was not detected, and the corresponding 2-hydrogenated indolizine 35 was obtained via beta-selenoxide elimination.…”

Section: Diorganyl Diselenides Promoted Selenocyclizationmentioning

confidence: 99%

“…Very recently, the group of Wang disclosed a regio-and chemoselective radical cascade cyclization of 1,6-enynes 82 and areneselenosulfonates 83a under 34 W blue LED irradiation in the air without any photocatalysts (Scheme 26). 34 Numerous substrates (82) were examined, and the corresponding cyclized products (84) were obtained in good to excellent yields. This reaction also proceeded smoothly using diaryl diselenides 83b with 1,6-enynes, and observed desired products with moderated to goods yields.…”

Section: Visible Light-promoted Selenocyclizationmentioning

confidence: 99%

Recent advances in tandem selenocyclization and tellurocyclization with alkenes and alkynes

et al. 2020

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“…We considered the aforementioned challenges and our ongoing research interest in photoinduced radical cascade reactions under mild reaction conditions 47 . Photoinduced organic transformations have potential economic and operational benefits due to their efficacy, commercial availability at a low cost and complementary radical generation compared to traditional metal/oxidants, additives and crucial requirements in chemical transformations 48 – 53 .…”

Section: Introductionmentioning

confidence: 99%

Photoinduced ynamide structural reshuffling and functionalization

Mutra

Wang

2022

Nat Commun

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The radical chemistry of ynamides has recently drawn the attention of synthetic organic chemists to the construction of various N-heterocyclic compounds. Nevertheless, the ynamide-radical chemistry remains a long-standing challenge for chemists due to its high reactivity, undesirable byproducts, severe inherent regio- and chemoselective problems. Importantly, the ynamide C(sp)-N bond fission remains an unsolved challenge. In this paper, we observe Photoinduced radical trigger regio- and chemoselective ynamide bond fission, structural reshuffling and functionalization of 2-alkynyl-ynamides to prepare synthetically inaccessible/challenging chalcogen-substituted indole derivatives with excellent step/atom economy. The key breakthroughs of this work includes, ynamide bond cleavage, divergent radical precursors, broad scope, easy to handle, larger-scale reactions, generation of multiple bonds (N-C(sp2), C(sp2)-C(sp2), C(sp2)-SO2R/C-SR, and C-I/C-Se/C-H) in a few minutes without photocatalysts, metals, oxidants, additives. Control experiments and 13C-labeling experiments supporting the conclusion that sulfone radicals contribute to ynamide structural reshuffling processes via a radical pathway.

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Alkene versus alkyne reactivity in unactivated 1,6-enynes: regio- and chemoselective radical cyclization with chalcogens under metal- and oxidant-free conditions

Abstract: Substituted pyrrolidine derivatives are obtained via regio- and chemoselective 5-exo-dig radical cyclization of unactivated 1,6-enynes with chalcogens under metal- and oxidant-free conditions.

Cited by 74 publications

References 70 publications

Light‐Mediated Seleno‐Functionalization of Organic Molecules: Recent Advances

Light‐Mediated Seleno‐Functionalization of Organic Molecules: Recent Advances

Recent advances in tandem selenocyclization and tellurocyclization with alkenes and alkynes

Photoinduced ynamide structural reshuffling and functionalization

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