Aza‐Michael Addition of Isatin and Phthalimide to Symmetrical Fumaric Esters in Ionic Liquid Media

Abstract

Highly efficient aza-Michael additions of isatin and phthalimide to symmetrical fumaric esters in ionic liquid media to produce the corresponding Michael adducts in excellent yields are described which were performed at 100 ℃ for 1-5 h. The results show that these aza-Michael additions are not effective with fumaric esters containing sterically hindered alkoxy groups.

Tetrabutylammonium Bromide Media Aza-Michael Addition of 1,2,3,6-Tetrahydrophthalimide to Symmetrical Fumaric Esters and Acrylic Esters under Solvent-Free Conditions

“…The reaction was carried out under solvent-free conditions at 100 °C with conventional heating. Both the ionic liquid used in our previous work [ 35 ], and the TBAB in the present work were found to be recyclable, however recovery of TBAB was easier than recovery of ionic liquid and the latter showed a slight decrease in catalytic activity do in this reaction we decided to replace the ionic liquid with TBAB.…”

“…For these reasons, and in keeping with our ongoing program on the development of cleaner pathways, we recently reported the aza-Michael additions between phthalimide and alkyl or aryl acrylates in the presence of tetrabutylammonium bromide (TBAB) and 1,4-diazabicyclo[2.2.2]octane (DABCO) under solvent–free conditions [ 34 ]. We also studied the Michael addition of phthalimide to symmetrical fumaric esters in ionic liquid media [ 35 ].…”

A catalyst-free and easy nucleophilic addition of certain isatins to sterically hindered 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone

“…17,18 The presence of an organocatalyst (triphenylphosphine (arsine), triethyl phosphite, DABCO, isocyanides) allows the addition of isatin to double carbon-carbon bonds of fumaric and acrylic esters. [19][20][21][22][23][24] In all cases formation of a carbon-nitrogen bond is realized. …”

Regioselective aza‐Michael additions of 2‐arylidene‐1,3‐diphenylpropan‐1,3‐diones with isatins: Synthesis of N‐diketone‐functionalized isatins

“…[ 4 ] One of the important applications for isatins is aza‐Michael addition to synthesize N ‐functionalized isatins. [ 5 ] However, the aza‐Michael addition direct using isatins as Michael donors are scarce because of their inactive properties. [ 6 ] The reported methods mainly utilized active isatin imines as substitutes.…”