Methyl 2,3-Butadienoate

[18913-35-4] C5H6O2 (MW 98.11) InChI = 1S/C5H6O2/c1-3-4-5(6)7-2/h4H,1H2,2H3 InChIKey = CYKLAQPZTQQBJU-UHFFFAOYSA-N (reactive electrophilic reagents for nucleophilic addition,2 Michael addition,3, 4 [2 + 2],5, 6 [2 + 3],7, 8 and [2 + 4]9, 10 cycloadditions, and hetero-Cope rearrangements4) Physical Data: bp 40 °C/14 mmHg. Solubility: sol common organic solvents. Form Supplied in: colorless liquid; not commercially available. Analysis of Reagent Purity: IR (film): 1965/1940, 1725 cm−1; 1H NMR (CCl4): 5.65–5.35 (HC(2)), 5.25–5.00 (2HC(4)), 3.68 ppm (OMe). Preparative Method: most conveniently obtained via a Wittig reaction of [E(R)CHPPh3]+X− or E(R)CPPh3 and RR′CHCOCl (R, R′ = H, alkyl) in the presence of Triethylamine in CH2Cl2.1 Alternatively, the Wittig reaction can be performed with the corresponding ketenes.11 Purification: rapid distillation under reduced pressure in a short-path distillation apparatus or column chromatography on Alox N with hexane/Et2O (9∶1). Hydroquinone may be added for distillation. Handling, Storage, and Precautions: can undergo polymerization and so should be stored in the presence of hydroquinone. For best results, it should be freshly distilled. Use in a fume hood.