1)      Ethyl 2-methylene-5-oxopentanoate

2)      Ethyl Acrylate

3)      DABCO

4)      1, 4-dioxane.

To a solution of ethyl 2-methylene-5-oxopentanoate (1.0 g, 6.40 mmol) in 1, 4 dioxane-H₂O (1:1, 25 mL) was added DABCO (0.71 g, 6.40 mmol) and ethyl acrylate (2.05 mL, 19.21mmol) at 30 ^ο C. Reaction mixture was stirred for 48 h and quenched by adding saturated NH₄Cl solution. The solution was extracted with ethyl acetate (50 mL), and ethyl acetate was evaporated to give crude product. Purification by column chromatography (n-hexane/ethyl acetate = 9/1) gave the pure product as colourless oil (1.35 g, 82 %).

¹H NMR (400 MHz, CDCl₃) δ 6.25 (d, J= 1.5 Hz, 1H), 6.17 (d, J= 1.6 Hz, 1H), 5.83 (t, J= 1.14 Hz, 1H), 5.59 (d, J= 1.5 Hz, 1H), 4.49-4.40 (m, 1H), 4.28-4.13 (m, 4H), 2.91 (bs, 1H), 2.49-2.31 (m, 2H), 1.91-1.68 (m, 3H), 1.35-1.22 (m, 6H).

¹³C NMR (100 MHz, CDCl₃) δ 167.3, 166.5, 142.2, 140.1, 125.1, 124.9, 70.5, 60.8, 34.9, 28.0, 14.0.

V. H. Jadhav, O. P. Bande, R. V. Pinjari, S. P. Gejji, V. G. Puranik, D. D. Dhavale, J. Org. Chem. 2009, 74, 6486-6494.