NHC-catalyzed cascade synthesis of 1-substituted 4-aryl-tetrahydroquinoline-2,5-diones

Highly diastereoselective synthesis of quinoline-2,5-diones and pyrazolo[3,4-b]pyridin-6(7H)-ones under microwave irradiation

“…Recently, Yao and co-workers reported the NHC-catalyzed synthesis of 4-aryl-tetrahydroquinoline-2,5-diones. 10 Pasha and co-workers developed a four-component approach for constructing quinoline-3-carboxylates using ZnO catalyst. 11 Kumar et al also described a domino protocol for the synthesis of quinoline-2,5-dione analogues.…”

Revealing the Similarities of α,β‐Unsaturated Iminiums and Acylazoliums in Organocatalysis

“…Ar elated NHC-catalyzed [3+ +3] annulation using cyclic enaminones was exposed by Yaoa nd co-workers. [37] Although both reactions are envisioned to proceed in mechanistically different pathway,t he formal aza-[3+ +3] annulation leading to the formation of the six-membered nitrogen heterocycle is noteworthy. [38] Acomparable trend in reactivity was observed with cyclic sulfonylimines.In2015, Liu, Zhang and co-workers disclosed atandem reaction of enals with N-sulfonylimines 35 using the secondary amine catalyst 37 leading to the enantioselective synthesis of tricyclic piperidines 36 in high yields and selectivity (Scheme 7).…”

Revealing the Similarities of α,β‐Unsaturated Iminiums and Acylazoliums in Organocatalysis

“…The reaction proceeds via the initial 1,2‐addition of 33 to 2 followed by a selective aza‐Claisen rearrangement and a subsequent amidation to afford the product. A related NHC‐catalyzed [3+3] annulation using cyclic enaminones was exposed by Yao and co‐workers [37] . Although both reactions are envisioned to proceed in mechanistically different pathway, the formal aza‐[3+3] annulation leading to the formation of the six‐membered nitrogen heterocycle is noteworthy [38] …”