Sodium hydride → Benzyl 2-methoxycarbonyl-4-ethoxycarbonyl-pent-4-enoate

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Reaction Steps

The title compound was prepared stepwise. In the first step, benzyl methyl malonate was reacted with an equimolar amount of ethyl 2-(bromomethyl)propenoate and sodium hydride in acetonitrile to give the product, benzyl 2-methoxycarbonyl-4-ethoxycarbonyl-pent-4-enoate, in 43% yield [1H-NMR (CDCl3) δ(ppm): 1.28 (t, 3H); 2.92 (d, 2H); 3.60 (s, 3H); 3.83 (t, 1H); 4.20 (q, 2H); 5.17 (s, 2H); 5.58 (s,1H); 6.18 (s, 1H) and 7.32 (m, 5H)]. In the second step, to a cooled suspension of sodium hydride (0.30 g, 0.01 mol, 80% dispersion in oil) in acetonitrile (20 mL), was added benzyl 2-methoxycarbonyl-4-ethoxycarbonyl-pent-4-enoate (2.68 g, 0.0084 mol). The resulting mixture was allowed to stir for 10 minutes before a solution of t-butyl 2-(bromomethyl)propenoate (1.85 g) in acetonitrile (5 mL) was added and stirring continued at room temperature overnight under nitrogen. After work-up, the title product (21) was obtained in 72% yield as a colourless liquid. 1H-NMR (CDCl3) δ(ppm): 1.28 (t, 3H); 1.46 (s, 9H); 2.94 (s, 2H); 2.96 (s, 2H); 3.58 (s, 3H); 4.16 (q, 2H); 5.10 (s, 2H); 5.60 (s, 1H); 5.67 (s, 1H); 6.17 (s, 1H) and 7.32 (m, 5H).

Provenance & Evidence