反应详情

The dl-threo-ritalinic acid used in step (i) may be prepared through multi-step process in which 2-chloropyridine and benzyl cyanide initially are coupled to form α-pyrid-2-yl-phenylacetonitrile. The resulting α-pyridyl-2-ylphenylacetonitrile then is hydrated in the presence of acid to yield α-pyrid-2-ylphenylacetamide which in turn is catalytically hydrogenated to yield α-piperid-2-ylphenylacetamide and then is hydrolysed and epimerized to dl-threo-ritalinic acid. The solvent used in the step (i) along with water may be selected from organic solvents. The solvent used to dissolve ester of tartaric acid may be selected from organic solvents. Conventional esters of tartaric acid used, may include dibenzoyltartaric acid and ditoluoyltartaric acid, the preferred one being (+)-dibenzoyltartaric acid of 0.2 to 1.6 eq to that of ritalinic acid, preferably, 1.06 eq in a solvent, preferably methanol adding at a temperature ranging preferably below 50° C., for a period preferably ranging from 5 min to 5 h. Heating the mass in step (ii) at reflux temperature preferably in 1 h to 2 h and filtering the mass through hyflo bed. The filtrate is cooled to a temperature preferably 20° C. to 25° C.