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ChemicalBook CAS DataBase List 3-CYCLOPENTYL-3-OXO-PROPIONIC ACID ETHYL ESTER

3-CYCLOPENTYL-3-OXO-PROPIONIC ACID ETHYL ESTER synthesis

6synthesis methods
-

Yield:24922-00-7 89%

Reaction Conditions:

Stage #1:hydrogen ethyl malonate with [2,2]bipyridinyl;n-butyllithium in hexanes at -65 - -55;
Stage #2:Cyclopentanecarboxylic acid chloride in hexanes at 20;

Steps:

6.6a
6a) Ethyl 3-cyclopentyl-3-oxopropanoate To a solution of monoethyl malonate (13.6 mL, 115 mmol) and a few milligrams of 2,2'-bipyridyl at between -55 and -65° C. was slowly added a 2.4 M solution of n-butyl lithium in hexanes (92.0 mL, 230 mmol). After the addition was complete, cyclopentanecarbonyl chloride (7.0 mL, 58 mmol) was added in portions. The solution was then allowed to stir while warming to ambient temperature and was poured into a mix of 1 N aqueous hydrochloric acid and ether. The layers were separated and the ether layer was washed three times with saturated sodium bicarbonate, dried over magnesium sulfate, concentrated and purified by chromatography (silica gel, 0-5% ethyl acetate in hexanes gradient elution) to afford ethyl 3-cyclopentyl-3-oxopropanoate (9.50 g, 89%). 1H-NMR (400 MHz, DMSO-d6) δ 4.06 (q, J=7 Hz, 2H), 3.60 (s, 2H), 2.99-2.91 (m, 1H), 1.78-1.47 (m, 8H), 1.15 (t, J=7 Hz, 3H).

References:

SmithKline Beecham Corporation US2008/96921, 2008, A1 Location in patent:Page/Page column 42

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