Diethyl Malonate → Diethyl 3-(benzyloxy)cyclobutane-1,1-dicarboxylate

Participants

Reaction Steps

Compound 1 was prepared according to the literature procedures of Avram, M., Nenitzescu, C. D. and Maxim, C. D. (1957) Chem. Ber., 90:1424 and Safanda, J. and Sobotka, P. (1982) Collect. Czech. Chem. Commun. 47:2440 with minor improvements. Malonic acid diethyl ester (258.6 ml, 1.703 moles) was added neat over a two hours period to a suspension of sodium hydride (51.10 g, 1.703 moles, Fluka N° 71614: 80% NaH in oil) in dioxane (1000 ml). This solution was stirred 90 min at room temperature. 1-Bromo-2-benzyloxy-3-chloro-propane (500 g, 1.789 moles) was added neat over a one hour period. The mixture was stirred for one hour at room temperature, followed by 24 hours at 125° C. After slow cooling to room temperature, a like quantity of sodium hydride was added neat in 5 g portions over one hour. The suspension was slowly heated to 125° C. and mechanically stirred for 120 hours at this temperature. The workup was as described in the literature references. Thus, compound 1 was first purified by distillation 172° C. at 0.6 Torr, followed by flash chromatography (tertiobutylmethylether/hexane=1/99 to 2/8) to afford 1: 382.5 g, 73.3% as a colourless oil.

Provenance & Evidence