Organic chemistry
1. Phthalimide-N-sulfonic acid and Isatin-N-sulfonic acid as highly efficient catalysts for the synthesis of bis-coumarins

Abdolkarim Zare; Jalal Sanjideh

Volume 6, Issue 4, pp. 325-460, Serial No. 21 , Autumn 2018, , Pages 416-422

http://dx.doi.org/10.30473/icc.2018.4612

Abstract
  Two highly efficient protocols for the production of bis-coumarins under solvent-free conditions have been introduced. The reaction of 4-hydroxycoumarin (2 eq.) with arylaldehydes (1 eq.) using phthalimide-N-sulfonic acid (PhtSA) or isatin-N-sulfonic acid (IsSA), as solid-acid catalysts, afforded the ...  Read More

Phthalimide-N-sulfonic acid and Isatin-N-sulfonic acid as highly efficient catalysts for the synthesis of bis-coumarins