Et3N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

SnCl2-mediated heterocyclization approach for the synthesis of benzisoxazole/quinoline-embedded β-carboline scaffolds

A Sn(II)-mediated facile entry towards construction of C-C/C-O and C-C/C-N bonds was devised. The developed reductive heterocyclization method is described for the synthesis of a diverse range of novel β-carboline C-1- and C-3-linked vinyl benzisoxazole analogues from the corresponding 2-nitro chalcones. In addition, the synthesis of β-carboline C-1-substituted quinolines (Nitramarine analogues) was achieved. The protocol was extended towards the formation of quinoline C-3-substituted benzisoxazole derivatives in good yields utilizing 2-alkynyl-3-formyl quinolines and 2-nitroacetophenone as templates. The scope of our strategy was demonstrated with the synthesis of a library of 56 novel molecules. The synthesized benzisoxazole derivatives had light-emitting properties to deliver a fluorescence quantum yield up to 33%.

Synthesis of 2-carboxyaniline-substituted maleimides from 2'-nitrochalcones

A practical, one-pot approach to 3-anilino-4-(het)arylmaleimides by simple heating of aqueous DMSO solution of 2'-nitrochalcones with potassium cyanide in the presence of formic acid has been developed. This new reaction provides effective access to a variety of β-substituted α-aminomaleimides which have recently become a subject of growing interest as small, easily modified and environmentally responsive fluorescent probes.