NOVELTY - A one-pot process for preparing rivaroxaban (I) or its isomeric form and/or racemic mixture, involves: a) reacting 5-chlorothiophene-2-carboxylic acid (IV) with a sulfonylating agent (Va) or (Vb) to produce a sulfonyl ester compound (III); and b) reacting the compound (III) with 4-(4-((5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (II) or its isomeric form and/or racemic mixture, or its acid addition salt, to produce the rivaroxaban (I).    USE - For preparing rivaroxaban (claimed), which is used as agent for the prophylaxis and/or treatment of thromboembolic disorders, particularly myocardial infarction, angina pectoris, reocclusion and restenosis after angioplasty or aortocoronary bypass, stroke, transient ischemic attacks, peripheral arterial occlusive diseases, pulmonary embolisms or deep venous thrombosis.    ADVANTAGE - The process is a one pot process, is commercially viable and industrially advantageous process, and prepares rivaroxaban in high yield and purity using novel intermediates. The process is an improved, commercially viable and environmentally friendly process of preparing rivaroxaban with high yield and purity, resolves the problems associated with the processes described in the prior art, and is suitable for large-scale preparation. The process exhibits desirable properties including non-hazardous conditions, is environmentally friendly and uses easy to handle reagents, has reduced process steps, reduced reaction time periods, reduced cost, greater simplicity, increased purity, and provides increased yield of the product, thereby enabling the production of rivaroxaban in high purity and with high yield. The process is carried out in a single pot using novel intermediates, and it involves shorter reaction times and reduced quantities of reagents and solvents; avoids the use of hazardous and corrosive chemicals like pyridine, thionyl chloride, and unstable acid chloride intermediate; avoids the use of tedious and cumbersome procedures like column chromatographic purifications, multiple isolations/recrystallizations, and recrystallizations using corrosive acids such as acetic acid; involves easy work-up methods and simple isolation processes, and there is a reduction in chemical waste; increases the purity of the product without additional purifications; and increases overall yield of the product.    DETAILED DESCRIPTION - A one-pot process for preparing rivaroxaban i.e. 5-chloro-N-(((5S)-2-oxo-3-(4-(3-oxomorpholin-4-yl)phenyl)oxazolidin-5-yl)methyl)thiophene-2-carboxamide (I) or its isomeric form and/or racemic mixture, involves: a) reacting 5-chlorothiophene-2-carboxylic acid (IV) with a sulfonylating agent of formula R-S(=O)2-Cl (Va) or R-S(=O)2-O-S(=O)2-R (Vb) to produce a sulfonyl ester compound of formula (III); and b) reacting the compound (III) with 4-(4-((5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholin-3-one (II) or its isomeric form and/or racemic mixture, or its acid addition salt, to produce the rivaroxaban (I).    R=alkyl, cycloalkyl, haloalkyl, aralkyl, or optionally substituted aryl.    INDEPENDENT CLAIMS are included for the following:    (1) new sulfonyl ester compound (III);    (2) preparing rivaroxaban (I) or its isomeric form and/or racemic mixture, involving: reacting a sulfonyl ester compound (III) with 4-(4-((5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl)phenyl)morpholine-3-one (II) or its isomeric form and/or racemic mixture, or its acid addition salt, to produce the rivaroxaban (I); and    (3) preparing sulfonyl ester compound (III).