Influence of
<i>N</i>
‐Substitution in 3‐Alkyl‐3‐hydroxyisoindolin‐1‐ones on the Stereoselectivity of Brønsted Acid‐Catalyzed Synthesis of 3‐Methyleneisoindolin‐1‐ones
作者:Nikola Topolovčan、Filip Duplić、Matija Gredičak
DOI:10.1002/ejoc.202100400
日期:2021.7.26
Brønsted acid-catalyzed dehydration of 3-alkyl-3-hydroxyisoindolin-1-ones is discussed. The reaction is efficiently catalyzed by methanesulfonic acid in acetonitrile and provides the corresponding 3-methyleneisoindolin-1-ones. The E/Z stereochemistry around the exocyclic double bond is in strong correlation with the size of the N-substituent. Selective formation of only one stereoisomer can be controlled
Palladium-catalyzed decarboxylative <i>ortho</i>-amidation of <i>O</i>-methyl ketoximes with oxamic acids
作者:Kun Jing、Peng-Cheng Cui、Guan-Wu Wang
DOI:10.1039/c9cc06460e
日期:——
The first palladium-catalyzed ortho-amidation of ketoximes has been developed with readily available, easy to handle and environment-friendly N,N-disubstituted oxamic acids as the amidation sources. When N-monosubstituted oxamic acids are used as the substrates, the formed ortho-amidated ketoximes undergo further intramolecular cyclization to provide 3-methyleneisoindolinones.
Aryl diazonium salts are versatile compounds known for their reactivity in various transformations. In this study, we explored the arylation of 3‐methylene isoindolinones using aryl diazonium salts. The objective was to develop a method for accessing 3‐benzyl‐3‐methoxyisoindolin‐1‐ones, a class of compounds with diverse biological activities and synthetic importance. Optimization of the reaction conditions revealed the significance of light irradiation for improved yields. The substrate scope investigation demonstrated the compatibility of various diazonium salts and N‐substituents on the 3‐methylene isoindolinone scaffold, yielding the corresponding methoxy lactams with high yields. Mechanistic insights were obtained by observing the effect of base and light irradiation. Two initiation mechanisms were proposed: in the presence of a base, the reaction could proceed even without light irradiation, while light irradiation was necessary in the absence of a base. DFT calculations were performed to elucidate the mechanism of the reaction and provide energetic considerations