The present disclosure provides a process for preparation of praziquantel of formula I, wherein the process can include the steps of (a) reacting benzyl amine with 2-chloro-N-phenethylacetamide of formula VI to obtain 2-(benzylamino)-N-phenethylacetamide of formula V (b) reacting 2-(benzylamino)-N-phenethylacetamide of formula V with haloacetaldehyde dimethylacetal to obtain 2-[(2,2- dimethoxyethyl)benzyl amino]-N-phenethylacetamide of formula IV (c) reducing 2-[(2,2-dimethoxyethyl)benzyl amino]-N- phenethylacetamide of formula IV in presence of a reducing agent to obtain 2-(2,2-dimethoxyethylamino)-N-phenethylacetamide of formula III (d) cyclizing 2-(2,2-dimethoxyethylamino)-N-phenethylacetamide of formula III in presence of an acid to obtain 4-oxo- 1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinoline of formula II and (e) acylating 4-oxo-1,2,3,6,7,11b-hexahydro-4H- pyrazino[2,1-a]isoquinoline of formula II with cyclohexanecarbonyl chloride to obtain praziquantel of formula I.
