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A protocol has been developed for the synthesis of six‐ and seven‐membered ring lactams fused to coumarins through a hydroaminocarbonylation reaction catalyzed by palladium. The catalytic system (PdBr2/Xantphos) provided a strategy for the synthesis of seven‐membered ring lactams with good isolated yield and regioselectivity. Control of selectivity by the substrate in the synthesis of six‐membered ring lactams was observed. Control reactions showed the importance of the hydrogen in the cyclocarbonylation reaction, and NMR data supported the role of the hydride palladium species as a catalytic precursor. A preliminary screening of the cytotoxic activity of coumarin‐fused lactams against six cancer cell lines was evaluated. The biological tests indicated that both the size of the heterocycle and presence of a substituent on the aromatic ring affected the inhibition of cell growth. [ABSTRACT FROM AUTHOR]

Seven‐membered ring lactones fused to coumarin scaffolds were obtained via a palladium‐catalyzed regioselective intramolecular alkoxycarbonylation under a CO atmosphere. Cyclocarbonylation of 3‐allyl‐4‐hydroxycoumarin derivatives was accessed in the absence of hydrogen gas, acidic conditions, or any other additives. The results of the control experiments revealed the importance of pKa of the substrate for initiating the reaction. [ABSTRACT FROM AUTHOR]

In their Research Article, K. Almaraz and M. Amézquita-Valencia prepared a new series of six- and seven-membered ring lactam fused to coumarin core via Pd-catalyzed hydroaminocarbonylation reaction under syngas conditions. Keywords: Cyclocarbonylation; Lactam; Palladium; Regioselectivity; Medium-sized heterocycles EN Cyclocarbonylation Lactam Palladium Regioselectivity Medium-sized heterocycles 1 1 1 08/23/23 20230821 NES 230821 B The Cover Feature b , designed by Hortensia Segura, illustrates a brave little cat (the catalyst) jumping onto a garden wall, crossing a seven-membered ring lactam fused to a coumarin scaffold. Cover Feature: Pd-Catalyzed Intramolecular Hydroaminocarbonylation of 3-Allyl-4-arylaminocoumarins: Synthesis of Six- and Seven-membered Ring Lactams Fused to the Coumarin Scaffold (ChemCatChem 16/2023). [Extracted from the article]