A chiral Brønsted acid-catalyzed highly enantioselective Mannich-type reaction of α-diazo esters with <i>in situ</i> generated <i>N</i>-acyl ketimines
作者:Rajshekhar A. Unhale、Milon M. Sadhu、Sumit K. Ray、Rayhan G. Biswas、Vinod K. Singh
DOI:10.1039/c8cc01436a
日期:——
A chiral phosphoric acid-catalyzed asymmetricMannich-typereaction of α-diazo esters with in situ generated N-acyl ketimines, derived from 3-hydroxyisoindolinones has been demonstrated in this communication. A variety of isoindolinone-based α-amino diazo esters bearing a quaternary stereogenic center were afforded in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). Furthermore
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
effective organocatalysts for the asymmetric Friedel–Craftsalkylation of indoles with 3-hydroxyisoindolin-1-ones. The corresponding products were obtained in excellent chemical yields (up to 99 %) with moderate to excellent enantioselectivities (up to >99 % ee after a single recrystallization). This is the first example of the catalytic asymmetric synthesis of valuable 3-substituted isoindolin-1-ones
corresponding quaternarycarbon-containing 3,3-disubstituted isoindolin-1-ones in good yields (up to 99 %) with good to excellent enantioselectivities (up to 95 % ee). The optical purity of the product was further improved after a single recrystallization. This protocol provides a convenient method for the catalytic asymmetric synthesis of valuable 3,3-disubstituted isoindolin-1-ones in high yields