Visible Light Mediated C(sp³)‐H Alkenylation of Cyclic Ethers Enabled by Aryl Ketone

Abstract

C−H alkenylation of cyclic ethers (THF, 1,4‐dioxane) using the readily available nitroalkenes as the alkenylating reagents has been developed. It allows the rapid access to the α‐alkenyl ethers with high E‐selectivity. The previous inaccessible α‐dienyl ethers are successfully obtained. Acyclic ether can also participate in this alkenylation process. The mechanism study reveals that alkenylation proceeded through a proton coupled electron transfer (PCET) process with a de‐nitration.

Chemo‐ and Regioselective Ring Construction Driven by Visible‐Light Photoredox Catalysis: an Access to Fluoroalkylated Oxazolidines Featuring an All‐Substituted Carbon Stereocenter

“…On the basis of above control experiments and literature survey, [21,22] a radical-type fluoroalkylation/ defluorination/annulation mechanism driven by visi-ble-light photoredox catalysis is depicted in Scheme 4a. First, the postulated photocatalytic cycle begins with single electron transfer (SET) from excited-state acriflavine* (E red = À 1.19 V vs SCE in MeCN) to perfluorobutyl iodide (2 a, E red = À 1.10 V vs SCE in MeCN) to produce an electrophilic n-C 4 F 9 radical and a radical cation PC * + by irradiation with visible light (see Supporting Information for details).…”

“…The key species of alkenylated compound E undergoes intramolecular Michael addition to produce the cyclized product 4. Other alternative rationales for the formation of alkoxy radical via a proton coupled electron transfer (PCET) process [21,22] or the formation of the radical-cation intermediate via oxidizing the double bond of compound E could be excluded. [23] The diastereoselectivity of this transformation is set during the course of cyclization mainly due to the configuration of chiral amino alcohol, enabling the intramolecular addition to Scheme 4.…”

Solvent-free synthesis of propargylamines: an overview

“…37 Methodologies like photocatalysis facilitated the incorporation of mild conditions and hence has widened the scope of different organic reactions. [38][39][40] Different type of solvents like halogenated solvents were used widely regardless of the environmental and health concerns they caused. Though they have many advantages like Gopinathan Anilkumar was born in Kerala, India and took his PhD in 1996 from the Regional Research Laboratory (renamed as the National Institute for Interdisciplinary Science and Technology NIIST-CSIR), Trivandrum with Dr Vijay Nair.…”

Combustion-Synthesized Porous CuO-CeO2-SiO2 Composites as Solid Catalysts for the Alkenylation of C(sp3)-H Bonds Adjacent to a Heteroatom via Cross-Dehydrogenative Coupling

“…Offering great benefits including improving atom economy, step efficiency, and reducing cost and waste, the CDC reaction is a more efficient synthetic protocol to access product molecules compared to traditional cross-couplings, which often require the use of prefunctionalized halides and organometallic reagents [1,[3][4][5]. In particular, α-C(sp 3 )-H of ethers and amines can be selectively coupled with C(sp 3 )-H or C(sp 2 )-H, leading to more complex structural motifs which have been usually found in natural products, pharmaceuticals, agrochemicals, biologically active molecules, and functional materials [6][7][8]. The CDC for the α-functionalization of ethers and amines is still a grand challenge because of the inert and ubiquitous nature of the C(sp 3 )-H bond.…”