Electrophilic Tetraalkylammonium Nitrate Nitration. II. Improved Anhydrous Aromatic and Heteroaromatic Mononitration with Tetramethylammonium Nitrate and Triflic Anhydride, Including Selected Microwave Examples

Abstract

A new one-pot nitration employing tetramethylammonium nitrate and trifluoromethanesulfonic anhydride in dichloromethane to provide a ready source of the nitronium triflate nitrating agent is presented. Rapid and selective nitration with a variety of aromatic and heteroaromatic substrates is achieved resulting in the synthesis of several novel organic compounds. A distinct advantage is the removal of undesired byproducts by aqueous workup. This very mild nitration permits large-scale syntheses and gives high isolated product yields that often require no further purification. This tetramethylammonium nitrate-based nitration also has been applied to microwave-assisted conditions, and the results with several compounds are outlined.

Kontrolliertes Erhitzen mit Mikrowellen in der modernen organischen Synthese

“… Oxidation von Thiazolidinen,199 elektrophile Nitrierung,200 Aminierung,201 Iodierung,87 Bromierung73 und Desalkoxycarbonylierung 202. NBS= N ‐Bromsuccinimid.…”

“…Unter Berücksichtigung einiger physikalischer Einschränkungen des dielektrischen Erhitzens mit Mikrowellen259 wurden zwei verschiedene Methoden für die Mikrowellen‐unterstützte Synthese mit >100 mL Volumen im geschlossenen Reaktionsgefäß entwickelt. Während einige Gruppen größere Multimode‐Geräte35, 42, 46, 137, 189, 200, 260 oder Monomode‐Reaktoren im Batch‐Verfahren verwendeten,261 versuchten andere, die mit der Maßstabsvergrößerung der MAOS verbundenen Schwierigkeiten mithilfe von (Multimode‐ und Monomode‐)Durchflusstechniken zu lösen 59. 262…”

Microwave Processing Techniques

“…Several authors have reported independently the feasibility of directly scaling reaction conditions from small-scale single-mode (typically 0.5-5 mL) to larger scale multimode batch microwave reactors (20-500 mL) without reoptimization of the reaction conditions [24,95,[150][151][152]. Several authors have reported independently the feasibility of directly scaling reaction conditions from small-scale single-mode (typically 0.5-5 mL) to larger scale multimode batch microwave reactors (20-500 mL) without reoptimization of the reaction conditions [24,95,[150][151][152].…”

Large-scale microwave-assisted ring-opening polymerization of ɛ-caprolactone

“…With reference to the successful small-scale examples, the larger scale microwaveassisted synthesis technology that can economically provide product on a multikilogram scale (or even higher) need to be developed for making it to become widespread technology in the future. Actually, for the ability of the direct homogenous heating of the reaction mixtures under microwave irradiation to facilitate direct scaling without heat and mass transport issues [7], several reports have demonstrated the feasibility of direct scaling reaction conditions from small-scale single-mode (0.5-5 mL) to larger scale batch modes (10-500 mL), such as multimode [8][9][10][11][12][13][14], monomode [15,16] and continuous-flow microwave reactors [17][18][19][20], without reoptimization of the reaction conditions. The larger scale microwave-assisted polymerizations (250-400 mL) have also been performed in domestic microwave ovens that equipped with reflux condensers [21,22].…”