An Efficient Process of Racemization of 3-(Carbamoylmethyl)-5-methylhexanoic acid: A Pregabalin Intermediate
journal contributionposted on 17.07.2009 by Anil B. Chavan, Golak C. Maikap, Mukund K. Gurjar
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A simple and cost-effective process for racemization of undesired (S)-3-(carbamoylmethyl)-5-methylhexanoic acid (9), produced during the resolution step, is described. The literature procedure is fraught with many difficulties including number of steps and hazardous reagents. We have developed a one pot process for the above-mentioned racemization of S-enantiomer. The basic objective is to convert S-enantiomer into the symmetrical glutarimide derivative followed by hydrolysis with an alkali. The transformation of 9 into glutarimide derivative (10) has been achieved with piperidine in refluxing toluene.