One-Pot Synthesis of Alkyl Indeno[1,2-b]quinoxalin-11-ylideneacetates under Solvent-free Conditions

Alum-catalyzed one-pot synthesis of dihydropyrano[3,2-b]chromenediones

“…However, the desired products were not found and obtained successfully. All of the structures were characterized by IR, 1 H NMR, 13 C NMR, MS and elemental analysis. In the 1 H NMR spectra, there was a missing proton, which was possibly OH.…”

“…Alum (KAl(SO 4 ) 2 ·12H 2 O), which is relatively nontoxic and inexpensive catalyst, has emerged as an efficient alternative catalyst for a variety of prominent organic transformations, such as the Biginelly 13 and Pechmann 14 reactions and also used for the synthesis of 1,8-dioxo-octahydroxanthenes, 15 isoquinolonic acids, 16 trisubstituted imidazoles, 17 1'H-spiro[isoindoline-1,2'-quinazoline]-3,4'(3'H)-diones, 18 1,3,4-oxadiazoles 19 and 1,5-benzodiazepines. 20 In this paper, we wish to report a rapid and highly efficient method for the synthesis of 2-(hydroxymethyl)-7,7-dimethyl-10-aryl-7,8-dihydropyrano [3,2-b] chromene-4,9(6H,10H)-dione in the presence of alum under solvent-free conditions (Scheme 1).…”

The chemistry of tryptanthrin and its derivatives

“…41 A solvent-free protocol under microwave conditions in the presence of potassium carbonate has also been reported. 42 Excess isatoic anhydride has been found useful to catalyze the synthesis by scavenging any developing water. 42 The addition of diisopropyl carbodiimide, dicyclohexylcarbodiimide, or 1,1'-carbonyldiimidazole/pyridine has also been employed for this purpose.…”

“…42 Excess isatoic anhydride has been found useful to catalyze the synthesis by scavenging any developing water. 42 The addition of diisopropyl carbodiimide, dicyclohexylcarbodiimide, or 1,1'-carbonyldiimidazole/pyridine has also been employed for this purpose. [34][35][36]44 Interestingly, in the presence of -cyclodextrin this procedure also works using water as a solvent.…”

“…[6][7][8]25,[34][35][36][37][38][39][40][41][42][43][44][45] This procedure has economic advantages, as many of the isatin and isatoic anhydride reactants are commercially available or can be easily synthesized by well established procedures.…”