Piramal Enterprises Limited

Ganesh Wagh

Milind Moreshwar Gharpure

Dhileepkumar Krishnmurthy

Galge Revanappa

Yogesh Zalte

Shashi Kant Tiwari

Manikrao Warpe

The present invention provides an improved process for preparation of the substantially pure (3aR,7aR)-4'-(benzo[d]isothiazol-3-yl)octahydrospiro[isoindole-2,1&#x2032;-piperazin]-1&#x2032;-ium methanesulfonate (referred to as compound-II), which is useful as a key intermediate for the synthesis of lurasidone ((3aR,4S,7R,7aS)-2-{(1R,2R)-2-[4-(1,2-benzisothiazol-3-yl)piperazin-1ylmethyl]cyclohexylmethyl}hexahydro-4,7-methano-2H-isoindole-1,3-dione). The process comprises reaction of the compound-III (as described herein) with the compound-IV (as described herein) in the presence of a solvent mixture selected from an alcohol and water; and a base The improved process for the preparation of compound II provides the product with total amount of unreacted compound-IV as impurity in less than 0.06% and the product with HPLC purity as &#x2265;99.8%. The process further refers purification of Lurasidone hydrochloride, wherein the product contains the residual acetone &#x3c;5000 ppm.

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Maharashtra, India

Ganesh Wagh