Abstract
Monoethyl malonate (1) and tert-butyl alcohol are esterified by catalysis with dicyclohexylcarbodiimide and 4-dimethylaminopyridine to yield ethyl t-butyl malonate (2). The ethoxymagnesio derivative (3) of the ester is condensed with b-carbomethoxypropionyl chloride to give the triester (4), which is decomposed by heating under vacuum in the presence of b-naphthalensulfonic acid to give ethyl methyl β-ketoadipate (5). Compound 5 is reacted with hydrogen cyanide,followed by hydrolysis of the cyanohydrin to give the free acid (6). Compound 6 is converted to homocitrate (7) by the use of an improved procedure.
Highlights
Our present work was initiated firstly by our aim to synthesize Mo-S complexes and Mo-Fe-S clusters, in which a Mo atom is coordinated by a homocitrate ligand, and to secondly test their nitrogen fixation
In our method monoethyl malonate and tbutyl alcohol are esterified at room temperature by the action of dicyclohexylcarbodiimide (DCC) in the presence of 4-dimethylaminopyridine (DMAP), which has been widely used as an efficient acylating catalyst in recent years, to yield ethyl t-butyl malonate [5]
We have provided the complete data determined with 1H-NMR, IR and MS of homocitrate, and these have never been seen in the previous related literature
Summary
We wish to report the preparation of homocitrate by our modified method as well as the results on the structural characterisation of the products. Our modified method (see reaction schemes 1-3) is based on the preparation of homocitrate introduced by Tucci et al [3]. In preparation of ethyl methyl β-ketoadipate (5) we used ethyl t-butyl malonate instead of Molecules 1998, 3 diethyl malonate to obtain the pure intermediate 5 so as to purify the end product (Schemes 1 and 2) [4].
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