3-Oxo-6-heptenoic acid ethyl synthesis

141-97-9 Synthesis

141-97-9
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$5.00/25g

106-95-6 Synthesis

106-95-6
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17605-06-0
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$75.00/250mg

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Yield: 86%

Reaction Conditions:

Stage #1:ethyl acetoacetate with sodium hydride in tetrahydrofuran at 0; for 0.5 h;Inert atmosphere;
Stage #2: with n-butyllithium in tetrahydrofuran;hexane at 0; for 0.5 h;Inert atmosphere;
Stage #3:allyl bromide in tetrahydrofuran;hexane at 0 - 20; for 2 h;Inert atmosphere;

Steps:

II. Typical procedure for the preparation of starting materials
General procedure: Methyl 3-oxohept-6-enoate (1a).¹ NaH (60% dispersion in mineral oil, 1.87g, 45.9 mmol) was washed three times with anhydrous hexane and suspended in anhydrous THF (120 mL). To this suspension was added dropwise methyl acetoacetate (3.13 g, 27.0 mmol) with stirring at 0 °C. The solution was stirred at 0 °C for 30 min. Then, n-BuLi (1.54 M in hexane, 28.5 mL, 43.2 mmol) was added dropwise to this solution at 0 °C. The brown solution was stirred at 0 °C for 30 min. Allyl bromide (2.70 mL, 29.7 mmol) was added dropwise to the resulting mixture at 0 °C. The reaction mixture was warmed up to room temperature and stirred for 2 h. The reaction was quenched by addition of saturated aqueous NH₄Cl solution, and the organic solvent was removed under reduced pressure. The residue was extracted three times with EtOAc. The combined organic layers were washed with saturated aqueous NaCl solution. The organic layers were dried over MgSO₄, and filtered through Celite. The filtrate was concentrated to afford a brown oil. The crude product was purified by distillation (200 Pa, 95 °C) to afford methyl 3-oxohept-6-enoate (1a) (3.58 g, 85%) as a colorless oil.

References:

Miyagi, Toshinori;Okada, Sho;Tada, Naoya;Sugihara, Masahiro;Kagawa, Natsuko;Takabatake, Tetsuhiko;Toyota, Masahiro [Tetrahedron Letters,2019,vol. 60,# 25,p. 1653 - 1657] Location in patent:supporting information

109-49-9 Synthesis