Diastereoselective construction of structurally diverse 2,3-dihydroquinolin-4-one scaffolds via redox neutral cascade [1,7]-hydride transfer/cyclization

Abstract

The pharmaceutically significant 2,3-dihydroquinolin-4-one scaffolds were constructed diastereoselectively and facilely via redox-neutral cascade Knoevengel condensation/[1,7]-hydride transfer/cyclization/transesterification in DCE from readily available methyl 2-aminobenzoacetate and diverse aldehydes, which features novel &...

The Cascade [1,5]-Hydride Shift/Intramolecular C(sp3)–H Activation: A Powerful Approach to the Construction of Spiro-Tetrahydroquinoline Skeleton

“…These valuable spirocyclic molecules have been well categorized according to the structural type of final products. Despite the significant developments that have been made in this growing field, some challenges still need to addressed: (1) The limitation of substrate scope, structural diversity of product, complex reaction conditions, and problem of large-scale capacity still limit its potential in organic synthesis ( Mori et al, 2014 ; Liu et al, 2018 ; Xing et al, 2020 ; Yuan et al, 2020 ; Guo et al, 2021 ; Sakai et al, 2021 ; Yang X. et al, 2021 ; Xie et al, 2022 ). (2) The current application of the cascade [1,5]-hydride shift/cyclization strategy mainly focuses on the construction of five- and six-membered spiro-tetrahydroquinoline.…”

Chemoselective and diastereoselective construction of 4-alkylidene-tetrahydroquinoline via a redox-neutral vinylogous cascade [1,7]-hydride transfer/6-endo-trig cyclization strategy

“…22 Presumably, more diverse skeletons can be constructed via the combination of vinylogous and cascade [1, n ]-hydride transfer/cyclization strategies. As a continuation of our research interest in developing highly efficient redox-neutral cascade processes for the facile construction of privileged heterocycles, 20,22,23 herein, we report a novel approach for accessing 4-alkylidene-THQs in a straightforward fashion via the piperidine-catalyzed vinylogous cascade condensation/[1,7]-hydride transfer/cyclization process with the in situ generated α,β,γ,δ-unsaturated dicyanoalkenes as the hydride acceptors (Scheme 1d). Compared with the previous studies, this method has fascinating features such as a novel product skeleton, high chemoselectivity and diastereoselectivity, facile introduction of 4-alkylidenyl motifs, employment of α,β,γ,δ-unsaturated dicyanoalkenes as novel hydride acceptors, and green and metal-free conditions with water as the only by-product.…”

Controllable construction of pharmaceutically significant scaffolds of 2,3-dihydroquinolin-4-one and benzoazepine-5-oneviaredox-neutral cascade hydride transfer/cyclization

“…, limited product skeletons, restricted to tetrahydroquinolines in most cases. 6 Very recently, the borane-catalysed [1,7]-hydride transfer was elegantly employed to construct 2,3-dihydroquinoline-4-ones 4 i featuring high yields, excellent diastereoselectivity and an unusual pattern for the [1,7]-hydride transfer 7 (Scheme 1a). Notably, the hydride acceptor moiety in the above example needed to be installed beforehand.…”