Steglich’s Base Catalyzed Three-Component Synthesis of Isoxazol-5-Ones

Non-catalytic regioselective synthesis of trans bis-pyrrolo isoxazole cycloadducts in water

“…13 While there exist several additional techniques for synthesizing oxazoles and isoxazoles, a multicomponent reaction among b-ketoesters, hydroxylamine hydrochloride, and aromatic aldehydes produces the product in higher yields in a single step. Several acidic and basic catalysts including boric acid, 14 potassium hydrogen phthalate, 15 DABCO, 16 metal-oxide nanoparticles, 17 pyridine, 18,19 and citrazinic acid 20 have been reported to catalyze the process.…”

Efficient and Aqoues Synthesis of 3,4-Disubstituted Isoxazol-5(4H)-one Derivatives Using Piperazine under Green Conditions

“…In this field, various catalytic systems and approaches have been reported for their synthesis, including deep eutectic solvents, 23 sulfonated graphene oxide (SGO), 24 boric acid, 25 nano-SiO2-H2SO4, 26 ZnO@Fe3O4, 27 I2, 28 CeCl3.7H2O, 29 silica-TLC grade, KI, 31 nano-MgO, 32 Ni(OAc)2.H2O, 33 Cu/thiocarbohydrazide-pr@SBA-15, 34 KBr, 35 sulfated tin oxide, and fruit juice. 37 In addition, various organic compounds, such as sodium acetate, 38 salicylic acid, pyridine, 40 starch solution, 41 potassium phthalimide (PPI), 42 2-hydroxy-5-sulfobenzoic acid (2-HSBA), sulfanilic acid, 44 potassium 2,5-dioxoimidazolidin-1-ide, 45 pyruvic acid, 46 imidazole, 47 succinic acid, potassium hydrogen phthalate (KHP), 49 2-aminopyridine (2-AP), 50 guanidine hydrochloride, pyrrolidinium dihydrogen phosphate, 52 pyridinium p-toluenesulfonate (PPTS), 53 Steglich's base, 54 and sodium benzoate 55 have been used as organocatalysts for the synthesis of a wide variety of 3,4-disubstituted isoxazol-5(4H)-ones. Nevertheless, these catalysts have several drawbacks: reactions require a prolonged reaction time, volatile organic solvent, microwave heating, sonication, and expensive or synthesis of some catalysts.…”