[74476-38-3] · C12H15N3O6 · Triethyl 1,2,4-Triazine-3,5,6-tricarboxylate · (MW 297.30)
(electron-deficient heteroaromatic azadiene capable of participation in inverse electron demand Diels-Alder reactions employed for the preparation of substituted pyridines)
Physical Data: bp 168-169 °C/1 mmHg, 173 °C/3 mmHg; n
Solubility: sol CHCl3, EtOAc, Et2O; insol H2O.
Form Supplied in: viscous, yellow oil.
Preparative Methods: a solution of ethyl oxalamidrazonate (88 mmol) in absolute EtOH (350 mL) is added dropwise to a stirring solution of diethyl dioxosuccinate (114 mmol) in absolute EtOH (86 mL) at 25 °C under N2. After addition is complete, the stirring is allowed to continue at 25 °C for 16 h before the solution is warmed at reflux for 2 h. The reaction mixture is cooled and the solvent is removed under reduced pressure. Chromatography (SiO2, 10-40% Et2O-hexane gradient elution) affords the pure reagent.2
Handling, Storage, and Precautions: can be stored at 25 °C but is hygroscopic and reacts with protic solvents; should be stored under anhydrous conditions.
Triethyl 1,2,4-triazine-3,5,6-tricarboxylate (1) is a highly electron-deficient heteroaromatic azadiene capable of participation in inverse electron demand Diels-Alder reactions with a variety of electron-rich dienophiles1 including enamines (eq 1),3 ketene-N,O-acetals (eq 2),4 alkynes (eq 3),5 benzynes,6 benzocyclopropenes (eq 4),7 and indoles (eq 5).8 The reaction is regioselective with the cycloaddition occurring across C-3/C-6 of the 1,2,4-triazine nucleus with the more nucleophilic carbon of the electron-rich dienophile preferentially attaching to C-3 of 1,2,4-triazine (eqs 1 and 2).3,4 A decrease or loss of regioselectivity is observed when the reacting sites in the dienophile become electronically and sterically less
Dale L. Boger & Minsheng Zhang The Scripps Research Institute, La Jolla, CA, USA
Dale L. Boger & Minsheng Zhang
The Scripps Research Institute, La Jolla, CA, USA