A Common, Facile and Eco‐Friendly Method for the Reduction of Nitroarenes, Selective Reduction of Poly‐Nitroarenes and Deoxygenation of N‐Oxide Containing Heteroarenes Using Elemental Sulfur. Issue 12 (13th March 2020)

• Record Type: Journal Article
• Authors: Romero, Angel H.; Cerecetto, Hugo
• Is Part Of: European journal of organic chemistry. Issue 12(2020)
• Page Start: 1853
• Page End: 1865
• Publication Date: 2020-03-13
• Subjects: Reduction -- Nitroarenes -- N‐oxide -- Heteroarenes -- Deoxygenation -- Green chemistry; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202000064
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : A transition metal‐free, environment‐friendly and practical protocol was developed either for the reduction of nitroarenes or for the deoxygenation of N ‐oxide containing heteroarenes. The reaction proceeded with the use of a non‐toxic and cheap feedstock as elemental sulfur in aqueous methanol under relatively mild conditions. Green chemistry credentials were widely favorable compared to traditional and industrial protocols with good E ‐factors and a low production of waste. The strategy allowed the efficient reduction of a large variety of substituted‐nitroarenes including various o‐ nitroanilines as well as selective reduction of various poly‐nitroarenes in excellent yields with a broad substrate scope. The protocol was successfully extended to the deoxygenation of some N ‐oxide containing heteroarenes, like benzofuroxans, phenazine N, N ' ‐dioxides, pyridine N ‐oxides, 2 H ‐indazole N 1 ‐oxides, quinoxaline N 1, N 4 ‐dioxides and benzo[ d ]imidazole N 1, N 3 ‐dioxides. A gram‐scale example for the synthesis of luminol, in green conditions, was reported. A solid mechanism of reaction was proposed from experimental evidences. Abstract : A facile and convenient protocol for the reduction of nitro‐arenes and deoxygenation of heteroarenes N ‐oxides under transition metal and additive free conditions has been developed. The strategy allows the selective reduction of poly‐nitroarenes as well as the efficient deoxygetaion of a variety of N ‐oxides containing heteroarenes including benzofuroxanes and phenzines with a broad substrate scope through a simply mixing operation.