Mo–Catalyzed One‐Pot Synthesis of N‐Polyheterocycles from Nitroarenes and Glycols with Recycling of the Waste Reduction Byproduct. Substituent‐Tuned Photophysical Properties

• Published in: Chemistry : a European journal Vol. 27; no. 54; pp. 13613 - 13623
• Main Authors: Hernández‐Ruiz, Raquel, Rubio‐Presa, Rubén, Suárez‐Pantiga, Samuel, Pedrosa, María R., Fernández‐Rodríguez, Manuel A., Tapia, M. José, Sanz, Roberto
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 24.09.2021; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Byproducts; Catalysts; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Cyclohexane; dioxomolybdenum; Fluorescence; N-heterocycles; nitroaromatics; Oxidation; photophysical properties; Physical Sciences; Quinoline; Quinoxaline; Quinoxalines; Reduction; reuse of waste; Science & Technology; Toluene; reuse of waste; BETA-AMINO ESTERS; photophysical properties; CASCADE REACTIONS; ANNULATION; EFFICIENT SYNTHESIS; dioxomolybdenum; nitroaromatics; WITTIG REACTION; REDUCING AGENT; ANTI-TUBERCULAR ACTIVITY; DERIVATIVES; N-heterocycles; BY-PRODUCT; CYCLIZATION
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202102000

A catalytic domino reduction–imine formation–intramolecular cyclization–oxidation for the general synthesis of a wide variety of biologically relevant N‐polyheterocycles, such as quinoxaline‐ and quinoline‐fused derivatives, and phenanthridines, is reported. A simple, easily available, and environmentally friendly dioxomolybdenum(VI) complex has proven to be a highly efficient and versatile catalyst for transforming a broad range of starting nitroarenes involving several redox processes. Not only is this a sustainable, step‐economical as well as air‐ and moisture‐tolerant method, but also it is worth highlighting that the waste byproduct generated in the first step of the sequence is recycled and incorporated in the final target molecule, improving the overall synthetic efficiency. Moreover, selected indoloquinoxalines have been photophysically characterized in cyclohexane and toluene with exceptional fluorescence quantum yields above 0.7 for the alkyl derivatives. A catalytic domino reduction / imine formation / intramolecular cyclization / oxidation allows the synthesis of a wide variety of biologically relevant N‐polyheterocycles. The reported process employs an inexpensive and nontoxic dioxomolybdenum(VI) complex as catalyst, easily available nitroarenes as starting materials and different glycols as reducing agents with reuse of the waste reduction carbonyl byproduct, which is embodied into the final compounds.