NOVELTY - Preparation (p1) of 4-(4-(5(S)-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (II) or its salt involves: reacting substituted ((oxazolidin-3-yl)-phenyl)-morpholin-3-one compound with a suitable optionally substituted benzyl amine to give corresponding compound (III) or its salt; and subjecting the compound (III) or its salt to reduction by using suitable hydrogenation catalysts.    USE - For the preparation of 4-(4-(5(S)-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (II) or its salt which is useful as an intermediate in the synthesis of morpolinone oxazolidine derivatives such as rivaroxaban (claimed) which is used as anticoagulant for the prevention of venous thromboembolism in adult patients undergoing elective hip or knee replacement surgery.    ADVANTAGE - The method obtains intermediates of rivaroxaban in an optically pure form; is simple, eco-friendly, cost-effective, reproducible, robust and well amenable on industrial scale; and uses easily available reagents. The method for the preparation of intermediates of rivaroxaban, avoids the use of potentially hazardous, expensive chemicals, the formation of isomeric and other process related impurities, while affording the desired intermediate products in high yield and purity.    DETAILED DESCRIPTION - Preparation (p1) of 4-(4-(5(S)-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (II) or its salt involves: reacting the substituted ((oxazolidin-3-yl)-phenyl)-morpholin-3-one compound of formula (IV) with a suitable optionally substituted benzyl amine to give corresponding compound of formula (III) or its salt; and subjecting the compound (III) or its salt to reduction by using suitable hydrogenation catalysts.    L'=a leaving group such as halo (F, CI, Br or I), methanesulfonate, benzene sulfonate, para-toluenesulfonate, 4- nitrobenzene sulfonate, 4-bromobenzene sulfonate and trifluoromethyl sulfonate;    R=optionally substituted benzyl.    INDEPENDENT CLAIMS are included for the following:    (1) preparation (p2) of the compound (III) or its salt involving reacting the substituted oxazolidin-phenylmorpholinone compound (IV) with a suitable optionally substituted benzyl amine;    (2) preparation of the compound (II) or its salt involving deprotecting the compound (III) or its salt by using hydrogenation catalysts (preferably palladium on carbon);    (3) 4-(4-((R)-5-chloromethyl-2-oxo-oxazolidin-3-yl)-phenyl)-morpholin-3-one compound of formula (III') or its salt, use as intermediate in the synthesis of morpholinone oxazolidine derivatives like rivaroxaban;    (4) an alternate method (m1) for the preparation of the compound (II) or its salt involving reacting (R)-epichlorohydrin (VIII) with a suitable azide derivative (d1) to afford (2R)-1-azido-3-chlorpropane-2-ol (VII); reacting the compound (VII) with phenyl chloroformate to give 3-chloro-(2R)-2-((phenyloxycarbonyl)-oxy)propyl azide (VI); reacting the compound (VI) with 4-(4-morpholin-3-onyl)aniline (V) to give 4-(4-((5R)-5-(azidomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (IIa); and subjecting the compound (IIa) to reduction using suitable reducing agents (r1); and    (5) preparation of the compound (II) or its salt involving subjecting the compound (IIa) to reduction using suitable reducing agents in the presence of suitable organic solvent.    R'a=optionally substituted benzyl or a group of formula (ia);    R1, R2=straight chain or branched 1-6C alkyl, straight chain or branched 1-6C alkoxy, halo (Cl, Br, I), nitro-, sulfonyl- or -OH;    R3=straight chain or branched 1-6C alkyl.