FeCl₃-Catalyzed Synthesis of 6-Thioxo-hexahydroindeno[1′,2′:4,5]imidazo[1,5-a]pyridin-12(6H)-ones via an Interesting [1,2] Oxygen Shift Pathway

Abstract

An iron-catalyst mediated one-pot multicomponent route for the synthesis of novel 6-thioxo-hexahydroindeno[1′,2′:4,5]imidazo[1,5-a]pyridin-12(6H)-one scaffolds has been developed using ninhydrin, L-proline, and aryl isothiocyanates in ethanol medium. This methodology offers an interesting [1,2] oxygen shift mechanism pathway via a number of ring-opening and ring-closing cascade steps to provide diverse substituted hexahydroindeno-imidazo[1,5-a]pyridinones in excellent to good yields. The stereochemistry of the proline ring is lost during the course of the reaction. This protocol is well acceptable toward both electron-accepting and electron-donating functionalities at the ortho-, meta-, and para-positions of the isothiocyanate moiety. Nonhazardous conditions, step economic, and easy operational process are the advantages of this methodology.

“On-water” synthesis of thioxoimidazolidinone-isatin/ninhydrin conjugates, followed by temperature-induced dehydration by a ZnMnO3@Ni(OH)2 nano-catalyst

“…In contrast, this specific “ D ” type intermediate (follow pathway A ) is formed when l -proline is utilized instead of methyl glycine. 35…”