Diethyl Malonate → (Cyclopentylmethyl)propanedioic acid

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Reaction Steps

A solution of diethyl malonate (36.91 g, 230.4 mmol), anhydrous methanol (400 mL), and NaOMe (25% in methanol, 49.79 g, 230.4 mmol) is stirred at reflux for one hour under nitrogen. Bromomethyl-cyclopentane (31.31 g, 192.0 mmol) is added to the mixture, and stirred for an additional 3 hours. A solution of NaOH (23.04 g, 576.0 mmol) in water (400 mL) is added, and the mixture is stirred for an additional 1 hour at reflux. The mixture is cooled, diluted with water, and extracted with ether. The ether layer is discarded, and the aqueous layer is acidified with 1N HCl to pH=1. The aqueous layer is extracted with EtOAc. The EtOAc layers are combined, dried over Na2SO4, and concentrated. This gives 2-cyclopentylmethyl-malonic acid (21.0 g, 59% yield) as a white solid.

Provenance & Evidence