2,2-Dimethoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazoline

Abstract

[138723-90-7] C6H12N2O3 (MW 160.17) InChI = 1S/C6H12N2O3/c1-5(2)7-8-6(9-3,10-4)11-5/h1-4H3 InChIKey = HEGRRSZUIAOCHY-UHFFFAOYSA-N (carbonyl 1,1-dipole equivalent: synthesis of heterocycles, e.g. hydroindolones, hydantoin, ring expansion, alkylate enols, formation of orthoformates, formation of thiiranes, and cyclopropanation) Alternate Name: 2,2-dimethoxy-5,5-dimethyl-2,5-dihydro-[1,3,4]oxadiazole. Physical Data: bp 51–52 °C/7 mmHg. Solubility: benzene, toluene, xylene, chlorobenzene, hexafluorobenzene, cyclohexane, and mesitylene. Form Supplied in: clear oil. Analysis of Reagent Purity: 1H and 13C NMR, IR, UV, elemental analysis. Preparative Methods: the title reagent can be prepared by oxidation of acetone(methoxycarbonyl)hydrazone with lead tetraacetate or phenyl iododiacetate. The hydrazone in methanol was added to a solution of lead tetraacetate in methanol at 0 °C and stirred at rt for 2 h. Then KOH was added and the reaction was stirred for an additional 2 h. Methanol was evaporated and the resulting solid was dissolved in CH2Cl2 and filtered through celite, washed with H2O, dried, and concentrated.1-3 Alternative preparation: the hydrazone and iodobenzene diacetate in methanol was stirred at 0 °C for 20 min, then the solvent was evaporated. The resulting crude product was dissolved in CH2Cl2 and the solution was washed with sodium hydrogen carbonate and then concentrated (eq 1).4, 5 (1) Purity: distillation under vacuum3 or column chromatography with neutral alumina or silica neutralized with a small amount of triethyl amine.4 Handling, Storage, and Precautions: shelf-stable,2 used in a fume hood. Evolves N2 gas upon fragmentation to the dimethoxy carbene.