反应详情

Using the procedure of Crombie et al., Journ. of Chem. Soc. Perkin Trans. 1, 464-471 (1979), a solution of ethyl acetoacetate (26 g, 0.20 mol), triethyl orthoformate (29.6 g, 0.20 mol) and acetic anhydride (41 g, 0.40 mol) was refluxed for 90 minutes. Distillation under reduced pressure gave the product (1): 26 g, 70% yield; bp=85°-98° C. at 0.5 mm Hg (The following value is reported in the Crombie et al. publication: bp=85° C. at 0.25 mm Hg); NMR (CDCl3) δ 1.2-1.5 (m, 6H), 2.4-2.5 (d,3H), 4.0-4.6 (m,4H), 7.7 (d,1H). The signals were split into pairs of closely spaced lines indicative of the cis and trans isomers.

1. distillationDistillation under reduced pressure