The cycloisomerization of readily available 2-alkynylbenzamides has been conveniently carried out with CuCl2 as catalyst under basic conditions in 1-ethyl-3-methylimidazolium ethyl sulfate ( EmimEtSO(4)) as an unconventional solvent. The process leads to (Z)-3-alkylideneisoindolin-1-ones in a chemo-, regio-, and stereoselective manner. The catalyst/solvent/base system could be recycled several times without appreciable loss of activity. The structures of representative products, that are, ( Z)-3benzylidene- 2-phenylisoindolin-1-one and (Z)-3-pentylidene- 2phenylisoindolin-1- one, have been confirmed by X-ray diffraction analysis, and DFT ( density functional theory) calculations have been carried out to clarify the roles exerted by the base and CuCl2 in favoring the reaction course leading to (Z)- 3-alkylideneisoindolinones.
Copper-Catalyzed Recyclable Synthesis of (Z)-3-Alkylideneisoindolinones by Cycloisomerization of 2-Alkynylbenzamides in Ionic Liquids
GIOFRE', Salvatore Vincenzo;ROMEO, Roberto;
2017-01-01
Abstract
The cycloisomerization of readily available 2-alkynylbenzamides has been conveniently carried out with CuCl2 as catalyst under basic conditions in 1-ethyl-3-methylimidazolium ethyl sulfate ( EmimEtSO(4)) as an unconventional solvent. The process leads to (Z)-3-alkylideneisoindolin-1-ones in a chemo-, regio-, and stereoselective manner. The catalyst/solvent/base system could be recycled several times without appreciable loss of activity. The structures of representative products, that are, ( Z)-3benzylidene- 2-phenylisoindolin-1-one and (Z)-3-pentylidene- 2phenylisoindolin-1- one, have been confirmed by X-ray diffraction analysis, and DFT ( density functional theory) calculations have been carried out to clarify the roles exerted by the base and CuCl2 in favoring the reaction course leading to (Z)- 3-alkylideneisoindolinones.Pubblicazioni consigliate
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