PROCESS FOR THE PREPARATION OF (S)-(+)-10,11-DIHYDRO-10-HYDROXY-5H-DIBENZ[b,f]AZEPINE-5-CARBOXAMIDE AND ESTERS THEREOF BY ENANTIOSELECTIVE REDUCTION OF 10,11-DIHYDRO-10-OXO-5H-DIBENZ[b,f]AZEPINE-5-CARBOXAMIDE

The present invention provides a novel process for the preparation of substituted optically pure (S)-(+)- or (R)-(−)-10-hydroxy-dihydrodibenz[b,f]azepines or derivatives thereof, starting from 10,11-dihydro-10-oxo-5H-dibenz[b,f]azepines using boronate esters or their derivatives. The present invention also provides use of thus prepared (S)-(+)- or (R)-(−)-10-hydroxy-dihydrodibenz[b,f]azepines for the preparation of their ester such as (S)-(−)-10-acetoxy-10,11-dihydro-5H-dibenz[b,f]azepine-5-carboxamide or (R)-(+)-10-acetoxy-10,11-dihydro-5H-dibenz[b,f]azepine-5-carboxamide. The present invention also provides novel solid state crystalline forms J1, J2, J3, J4 and amorphous form of eslicarbazepine and the process for the preparation thereof. Also, the present invention provides novel solid state crystalline form and amorphous form of eslicarbazepine acetate and the process for the preparation thereof. The novel solid state forms of eslicarbazepine are useful for the preparation of derivatives of eslicarbazepine such as eslicarbazepine acetate.